Category: Bug of the Week

Bug o’the Week – Dogwood Scurfy Scale

Bug o’the Week
by Kate Redmond

Dogwood Scurfy Scale

Howdy, BugFans,

If asked to describe a Red-osier dogwood shrub, lots of people would say “it has red bark with white lumps on it.”  It does – but it doesn’t.

Some of our most un-bug-like bugs are the scale insects.  There are lots of them worldwide – about 8,400 species in 36 families.  They’re called scales because they (the females, anyway) cling, limpet-like, to their food plant, protected under a waxy covering that looks fish-scale-ish.  They’re sexually dimorphic (“two forms”), and adult males – in the species where males exist – are often tiny and gnat-like.  If your basic definition of an insect is “six legs, some wings, and three body parts that are divided in segments” you’ll have to suspend it a bit for the scales.

Their nearest relatives are aphids, whiteflies, jumping plant lice, and phylloxera bugs.

They hatch from eggs that the female lays under her body (or they are viviparous – popped out “live”), sometimes fertilized with the help of a male and sometimes produced by parthenogenesis (“virgin birth”), and a very few species are hermaphroditic (they have dual equipment and can self-fertilize, and so a single individual can create a whole population).  Six-legged when they hatch, scales enjoy two short, mobile instars (they’re called “crawlers”), during which they disperse, but their legs are short, so they don’t go far without help (crawlers may also be blown around by the wind).  Then the tiny females settle down, attach to a host, and lose their legs, generally staying put for the rest of their lives.  The short-lived males must find females where they sit, and although he may be winged, his wings are not good for much, so he comes on foot.  There are generally several generations per year.

Scales are vegetarians, feeding on plant sap that they suck from leaves or branches.  Some are found only on specific hosts and others are more generalist feeders, and although a very few species feed on mosses, lichens, and algae, as a group, they’re fond of the woody plants.  Their predators include some ladybugs and lacewings, and a few parasitoid wasps whose larvae consume the insect (they target younger scales) or the eggs under the scale.  There are scale insects that are serious plant pests, scale insects that are used to control invasive plants, and scale insects that are “cultivated” because they’re used to produce shellacs, waxes, and red dyes. 

The two, big divisions of scale insects are “cushiony” and “armored” scales.  Cushiony scales tend to be lumpier than armored scales, and they’re permanently attached to their waxy covering.  The excess sap that they consume, released as a sweet fluid called “honeydew,” attracts other insects to feed on it, and some species of scale are cared for by ants that protect the scales from predators, harvest the honeydew, and help the crawlers find fresh twigs.  The downside of honeydew is that sooty mold grows on leaves where its sticky sweetness falls, which interferes with photosynthesis and isn’t very wholesome looking.  A species of cottony scale was featured in a BOTW years ago https://uwm.edu/field-station/bug-of-the-week/cottony-scale-family-coccidae/

Dogwood scurfy scales are armored scales, and armored scales are in the family Diaspididae, the largest scale family (2650 species).  Armored scales feed on hosts from 180 plant families.  They’re not attached to their waxy cover, are smaller and flatter than cottony scales, and they don’t produce honeydew.  Their tough – armored- coverings may be round, elliptical, or oyster shell-shaped and may have concentric rings/ridges.  The female incorporates the shed skins from her crawler stage into her growing shell, and the wax is made and shaped by a structure called the pygidium at the rear of the abdomen.  The critter below the scale has knob-like antennae, no legs, and little distinction between head and thorax.  

Not surprisingly, with so many species of armored scales, there are many different lifestyles.  In general, she lays her eggs or live young under her scale, which has a slit at the rear that allows them to exit.  Her eggs overwinter under the shelter of her scale, though she’s no longer alive when they hatch.

The BugLady saw a paper that said that some armored scales may get around by phoresy – hitchhiking – sticking to their six-legged taxi cabs (the study identified a fly, a ladybug, and an ant) with the help of a few “suction-cup”-tipped hairs on each of their legs

FUN FACT ABOUT ANT PARTNERSHIPS

An odd relationship has evolved between a species of African ant and a species of armored scale (which, remember, have no honeydew to trade for ant favors).  The ants shelter the scales in the galleries/tunnels they live in under tree bark – the ants are so specialized that they spend their whole lives there.  The scales no longer need protection from the elements or from predators, so most of them are “naked,” though some still make wax and other scale-building materials that the ants eat along with the crawlers’ shed skins and various scale “excretions.”  The whole thing hinges on the ant queen finding a suitable host tree and rounding up crawler-aged scales during her brief nuptial flight.

As the poet Muriel Rukeyser once said, “The world is made of stories, not atoms.”

SCURFY DOGWOOD SCALE/RED-OSIER SCALE INSECT

The BugLady started nibbling around the edges of this episode at least three years ago and hit a brick wall pretty fast.  The Extension and Horticultural sites mostly said – “Yup, dogwoods get scales” but offered no names or biographies, so, the original iteration of this BOTW was something like, “These are dogwood scurfy scales – they’re everywhere, but no one’s written anything about them – thanks as always to PJ at the Insect Diagnostic Lab in Madison for pointing the BugLady toward an ID.” 

But the BugLady could never do that, so…..

In her initial search for a name, the BugLady came across the pine leaf scale (Chionaspis pinifoliae https://bugguide.net/node/view/361628/bgimage) that looked similar, but she thought it was unlikely to be her scale because, well, pine needles.  The dogwood scale suggested by PJ is Chionaspis corni; in the same genus, but when you Google Chionaspis corni, most hits are for Chionaspis pinifoliae.  Bugguide.net lists no other genus members and although the dogwood scurfy scale is common here, does not even show the genus as occurring in Wisconsin (buggide’s caveat about its range maps is “The information below is based on images submitted and identified by contributors. Range and date information may be incomplete, overinclusive, or just plain wrong”).

Just to make things interesting, the accepted spelling of the genus name (since 1868) is Chionaspis, but over the years it has officially been misspelled by later taxonomists as Chianaspis, Chiomaspis, and Chionapsis.

The BugLady checked the wonderful Illinois Wildflowers website https://www.illinoiswildflowers.info/ and found the dogwood scale (along with several other species of scale including the willow scale and the Gloomy scale) mentioned in the Faunal Associations sections of the write-ups of red-osier and flowering dogwoods and several other dogwood shrubs. 

And one more thing – “scurfy” means rough or scaly or covered with scurf, and a “scurf” is a flake, scale or dandruff.

Whew!

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Common Buckeye Butterfly rewrite

Bug o’the Week
by Kate Redmond

Common Buckeye Butterfly rewrite

Howdy, BugFans,

The BugLady originally wrote about the Common Buckeye in January of 2009, but she thinks she might have given it short shrift (due to insufficient scholarship), so here’s a rewritten version with new words and new pictures.

The first thing to know about Common Buckeyes is that they are not Yankee butterflies – they are Southerners (from a largely tropical genus) that recolonize God’s Country in varying numbers from year to year and produce a two or three broods here, depending on whether spring and/or fall is long and mild.  But they are not very “freeze-tolerant,” and they can’t survive Wisconsin winters in any stage, so they wander back south in the fall.  Brock and Kaufman, in their Field Guide to Butterflies of North America, report that fall migrations of Common Buckeyes, especially on the Atlantic coast, can be spectacular.  The BugLady saw some out on the prairie as recently as a week ago – they always see her and her camera before she sees them (with their wings closed, they’re pretty well camouflaged), and they fly farther down the trail to wait for her.

The Common Buckeye (Junonia coenia, aka Precis coenia) (not the Ohio buckeye – that’s a tree) belongs to the Order Lepidoptera (“scaled wings”) which includes the butterflies and the moths.  Of the 12,000 species of Lepidoptera in North America north of Mexico, only about 700 are butterflies.  Along with the usual six-legs-three-body-parts insect stuff, moths and butterflies have in common four wings that are covered with easily-rubbed-off scales (the upper surface of a butterfly’s wing often has a different pattern then the lower surface does), and mouthparts in the form of a coiled tube called a proboscis that is used for feeding on liquids like nectar and sap.  Caterpillars chew; butterflies and moths sip. 

Rules of thumb for telling them apart are that (generally) butterflies sit with their wings held out to the side or folded vertically above their bodies, and moths hold their wings flat over or wrapped around their body.  Butterflies have a thickened tip/knob on the end of their antennae; moths’ antennae may be bare or feathery but are never knobbed.  Butterflies are active by day (though the BugLady had night-feeding Northern Pearly-eye butterflies who hadn’t read that part of the playbook), and moths are generally active in late afternoon and through the night.  Some moths have bright colors and patterns, but as a group, they tend to be drab – what birders call “LBJ’s” – “Little Brown Jobs.”  Because of their pigmented and/or prismatic scales, many butterflies are the definition of the word “dazzling.” 

Buckeyes belong to the “Brush-footed butterfly” family Nymphalidae, a large group of strong, colorful fliers whose front legs are noticeably hairy and are reduced in size (leading to another nickname – “four-footed butterflies”).  There are a number of brush-foots that migrate and others that, contrary to the usual insect practice, overwinter as adults.  Many Nymphalid caterpillars are nocturnal and spiny.  

The “Butterflies of Massachusetts” website says of this beautiful butterfly that “The Halloween-costumed Buckeye wears the colors of fall in New England.”  Buckeyes are named for the eyespots on their wings, which are reminiscent of the spots on buckeye nuts.  Many members of the genus Junonia have eyespots to scare away predators, and an eyespot can even be seen in the Buckeye’s pupal wing case. 

Both the caterpillar and the adult are variable in color – an adult whose underwing surface is tan is from an early summer generation, and one whose underwing is rosy is from the final brood of the year – the color change is controlled by genes and is a response to the temperatures that the caterpillar is exposed to.  There is no other butterfly species in Wisconsin that can be mistaken for them. 

Buckeyes are sun-lovers, butterflies of sunny habitats like open fields, disturbed areas, trails, edges, and grassy dunes, where they often perch on the ground.  “Butterflies of Massachusetts” speculates that this species has become more common since the European settlers cleared the great forests for agriculture, and notes that it is one of our native butterflies that has adopted a non-native “weed” (English plantain) as a food plant.  Adults sip nectar from dogbanes and from those confusing fall composites (asters and goldenrods), and they sip fluids from decaying fruit. 

Males are feisty and territorial, chasing other flying objects, both butterfly and non-butterfly alike.  He scouts for females from a perch on the ground or on low vegetation.  After mating, females oviposit on leaves and leaf buds of host plants – mostly members of the plantain (the lawn plant, not the banana relative) and snapdragon families.  Caterpillars https://bugguide.net/node/view/1939097/bgimage are solitary and non-aggressive, even when they bump into another caterpillar on the same plant.  The pupae https://bugguide.net/node/view/2214613/bgimage are said to look like bird poop (pretty fancy bird poop, indeed!). 

Caterpillar food plants often contain toxic chemicals (iridoid glycosides) that besides being very bitter, will literally stunt the growth of a predator that eats a caterpillar – chemicals that, conversely, make the caterpillars hungry.  Chemicals that, when the female senses them, will stimulate her to oviposit.  Predators seem to sense the presence of the glycosides and prefer caterpillars with low/no levels of them.  Caterpillars must be careful of getting too much of a good thing – excessive amounts of iridoid glycosides can affect their immune system negatively.

Ain’t Nature Grand!

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Two Enigmatic Insects

Bug o’the Week
by Kate Redmond

Two Enigmatic Insects

Howdy, BugFans,

In her program about insect Natural History, the BugLady says to the audience “so – we’ve been studying insects for hundreds of years – we’ve got it all nailed down, right?”  Sure.  The BugLady has had some interesting adventures with insects this year.  Even if she can identify them (a big “if” – the X-Files are bursting), not all of them lead transparent lives (“What is it?” should, after all, not be the last question we ask about an organism, it should be the first, and the answer helps open a bunch more doors).  The BugLady frequently writes about bugs who are caught in a classification dust-up.  Here are two poster children for “temporarily displaced” insects.

THE BRACKEN BORER MOTH (maybe) 

When the BugLady photographed this beautiful moth on her back porch rail in mid-September, she knew that it was in the genus Papaipema (the borer moths) (in the Owlet moth family Noctuidae), but which species?  Caterpillars of a few Papaipema species are somewhat generalist feeders, but many are highly specific about host choice, as is evidenced by names like Blazing star borer, meadow rue borer moth, pitcher plant, burdock, iron weed, hop, and rattlesnake master borer, Joe-Pye, aster, columbine, sunflower, coneflower, turtlehead, royal fern, and cinnamon fern borer, and more (there are 50 species). 

It’s a genus of moths that flies and reproduces in late summer and early fall and that are generally found near their host species.  The eggs overwinter and hatch in spring, and the modus operandi of their rarely-seen caterpillars https://bugguide.net/node/view/1127727 is to bore into the roots, rhizomes, and/or stems of their (non-woody) host plants, feed in seclusion, pupate in summer, and emerge in fall.  Bugguide.net remarks that “Many species are rare or locally distributed. Numbers have generally declined since historical times due to loss of wetland and prairie habitat, and the resulting scarcity of particular food plants upon which some species depend (the names of various Papaipema species appear on a number of state lists of “species in greatest need of conservation”).”  Wagner, et al, in Owlet Caterpillars of Eastern North America write that “the genus seems to be speciating rapidly as evidenced by the number of species that are known to be geographically localized….  As might be expected of a large genus with specialized habits, a number of species seem to be slipping toward extinction.  Close to a third of Connecticut’s 30 species have not been seen in more than three decades…”

So, who was BugLady’s visitor?  It looked an awful lot like the Bracken Borer moth (Papaipema pterisii) (https://bugguide.net/node/view/1443121/bgimage), whose food plant is Bracken fern (https://illinoiswildflowers.info/grasses/plants/bracken_fern.htm).  The problem was that the BugLady hasn’t seen any bracken fern in her neighborhood, but she and the moth were 20 feet away from lots of Ostrich fern.  Is there an Ostrich fern borer? 

She found a picture of a “potential” Ostrich fern borer https://guides.nynhp.org/ostrich-fern-borer-moth/, and the plot thickened.  It hasn’t really been described or named yet (it’s one of several possibly-emerging new Papaipema species), but the DNRs and Natural Heritage Departments of a number of Northeastern states refer to it as “unnamed Papaipena species #2” or call it “Papaipema sp. 2 nr. Pterisii,” and they’re keeping an eye on it.  It’s described as being larger and more richly colored than, and flying a bit later in the fall than the Bracken fern borer.  It feeds on Ostrich fern (first in the stem and later in the roots), and its pupae are found in the soil at the base of Ostrich fern stalks.  You can’t tell the difference between it and the Bracken borer in a photograph.

But what is its status in Wisconsin, the BugLady wondered?  She asked PJ, and PJ asked Les, and Les recommended sticking with Bracken borer for now – it’s not known if the Bracken borer might be using more than one host, and identifications shouldn’t be made just on the basis of host plants.  It is likely not a valid species, said Les, but a publication due out in early 2025 may shed more light on it.  Thanks, Gentlemen.  Stay tuned.

YELLOW-FACED SWIFTWING – Version 1  

How do you tell a fly from a bee?  Easy – hymenopterans (bees, wasps, etc.) have four wings and flies have two.  Except that, hymenopterans typically perch with their wings more-or-less stacked, and very few are cooperative enough to spread their wings so that we can count them.  The BugLady recognized this bumble bee mimic as a fly because of its (wimpy) antennae and because of the large, flattened eyes https://bugguide.net/node/view/1838687/bgimage.  One entomologist calls them “wanna bees.”  Here’s a bumble bee for comparison https://bugguide.net/node/view/1221268/bgimage.

It’s a syrphid/hover/flower fly (family Syrphidae) in the genus Volucella (the Swiftwings), a genus that according to most internet sources has four species in North America.  Probably a Yellow-faced Swiftwing (Volucella facialis) (if it’s not, it’s an Eastern Swiftwing (V. evecta).  Members of the genus look a little “hippy” (no judgement) (“broad-bodied,” says one source), have triangular faces, and their “arista” (the bristle that juts off of the antenna) is plumose (feathery) https://bugguide.net/node/view/1870769/bgimage.  Here’s a glamour shot https://bugguide.net/node/view/1494989/bgimage. 

YELLOW-FACED SWIFTWING – Version 2   

So, the BugLady had settled on the narrative above, but then she found an article from the University of California, written in 2020, that pretty much upended it.  According to entomologist Andrew Young, there is only one species of Volucella fly in North America, and it’s Volucella bombylans, whose range stretches across Eurasia (it’s called the Bumblebee hover fly in England), the Near East, and North America.  There was no suggestion of whether it had or had not immigrated here from someplace else.  All the “other” Volucellas in this country, says Young, are simply varieties of V. bombylans, and they probably exist as a “species complex,” a group of closely-related species that look so much alike that we can’t differentiate among them and that may be able to hybridize.  Hold your horses, say other biologists, there are no species complexes, it’s just that our meager observational skills don’t yet allow us to detect their differences.  Scott King, in his The Flower Flies of Minnesota (2021), writes that “the Volucella bombylans species complex was only recently unraveled into three Nearctic [New World] species, two of which [V. facialis and V.evecta] live in Minnesota.”

Whatever the name, the life histories of these flies is similar – they lay their eggs in the nests of social wasps and especially of bumble bees (whose nests they have no trouble entering).  When the eggs hatch, the fly larvae are detritivores, feeding on organic debris in the nest, including dead bees, and on bee larvae, too, and some eat bee and wasp pupae within the nest.  They are inquilines – animals that live in another animal’s space (from the Latin word “inquilinus,” meaning tenant or lodger).  Some inquilines don’t eat their hosts, but some do.  The esteemed French naturalist and entomologist Henri Fabre (1823 to 1915) wondered how the larvae could survive inside a wasp nest: “What has it to make itself thus respected?  Strength?  Certainly not.  It is a harmless creature which the Wasp could rip open with a blow of her shears, while a touch of the sting would mean lightening death.” 

Adult Volucella are nectar feeders that, says Wikipedia, like to sun themselves on leaves, and it also says that the genus is strongly migratory and that males are often territorial.  Syrphids are important pollinators. 

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Oil Beetle Adventures

Bug o’the Week
by Kate Redmond

Oil Beetle Adventures

Greetings, BugFans,

When the BugLady was walking at Riveredge towards the end of September, she came to a fork in the trail and thought “if I go left, I’ll get back to the car faster, but if I go right, I’ll see something good.”  So she did, and she did.

Along a 15 foot stretch of trail, she found a half-dozen Oil beetles in the grass (including one pair in flagrante delicto).  She suspects that some of the motionless females may have been ovipositing.  And then she looked closer.

Oil beetles, which are blister beetles (family Meloidae) in the genus Meloe, are odd-looking beetles – inky blue-black, soft, and bulbous (“bloated,” said one source; “like a black clove of garlic,” said another), with astonishing antennae.  Their elytra (wing covers) are very short, because they actually have no hind wings to cover.  The name “Oil beetle” comes from the oily drops of haemolymph (bug blood) (aka hemolymph, but the BugLady loves the British spelling) that ooze from their joints when they’re alarmed https://bugguide.net/node/view/408611/bgpage.  Look, but don’t touch – the oil contains cantharidin, which is one of their Super Powers.  We have met blister beetles in previous BOTWs – here’s Blister Beetle 101 https://uwm.edu/field-station/bug-of-the-week/blister-beetle/. 

It’s a genus that has somewhat northern proclivities, with many species present across Canada. 

They are, oddly, measured from the front of the head only to the far point of the elytra, rather than to the end of the (often-distended) abdomen.  Females may be as long as 1 ½” and males are smaller. 

When a young Meloe beetle’s fancy turns to love, he finds a female, climbs aboard, and rubs her antennae with his, releasing a pheromone that calms her.  Bugguide says, “In males of some species mid-antennal segments are modified, and the c-shaped ‘kinks’ (antennomeres V–VII) grasp female antennae during pre-mating displays.”  He transfers some cantharidin to her in his sperm packet, and she coats her eggs with it to protect them from predators. 

In many insect species with predatory/parasitic larvae, Mom delivers the eggs to their eventual host, but Meloe beetle larvae are on their own.  When they hatch, the super-active larvae, called triungulins, climb up onto flower heads and wait for bees to come along.  Each species of Meloe beetle targets a particular genus or species of solitary, ground-nesting bee, and when the right one comes along, the larva jumps on.

Some sources say that the larva targets males, riding with him until he has a liaison with a female, and then switching to her.  Other sources say that it ignores males and only attaches to females.  The ultimate goal is access to the female’s nest, where it acts as a kleptoparasite, eating the food cache she has put by for her young (and sometimes eating her eggs, too).  After it has gained entry to its host’s nest, the rest of its larval life is sedentary. 

Oil beetles are usually seen moving slowly along the ground or on low vegetation.  Adults feed on plant material, including pollen, nectar, and leaves. 

Despite the toxicity of cantharidin, these beetles have been used in traditional medicines in East Asia, especially China, to treat external conditions like boils, warts, bruises, and fungal skin infections, and internally for cancer, liver issues, colds, and to induce abortions.  

According to the Montana Natural History Center website, “For their diverse uses and fascinating ecology, oil beetles were named the 2020 insect of the year by an entomological society in Europe.”

Bugguide.net says that there are 22 species in the genus Meloe in North America, and the BugLady isn’t quite sure which species she found.  Some are primarily active in spring and others in fall, but some may be found in both seasons, depending on the phenology of their host bees.  Fall candidates in Wisconsin include:

  • The Impressive oil beetle (Meloe impressus), about which the Minnesota Seasons website says “The first stage (triungulin) is mobile on plants. The entire hatched group climbs to the top of a plant and forms a cluster in roughly the shape of a female ground bee. It then exudes a chemical scent that mimics the pheromone of a female bee. When a male bee attempts to mate with the mass, some of the larvae attach themselves to its hairs. When the male mates with a female bee some of the larvae attach to the female. These remain on the female while she builds a nest, then detach and begin feeding on newly laid bee eggs.”  
  • The American/Buttercup oil beetle (Meloe americanus), which lays its eggs near the base of a flower (bugguide says that females of these first two species are hard to tell apart). 
  • The Short-winged blister beetle (Meloe campanicollis), which may persist into late fall.
  • And Meloe exiguus (no common name), about which the BugLady could find nothing.

And when she put her pictures up on the monitor and looked closer?  Besides seeing a lot of green frass (bug poop), the BugLady saw that one female was being bothered by some exceedingly small biting midges (family Ceratopogonidae).  She sent the pictures to PJ Liesch (“the Wisconsin Bug Guy”), Director of the UW Madison Insect Diagnostic Lab, who shared some papers with her about a genus of biting midges (Atrichopogon) that have been associated with Meloe and other blister beetles (and shared her delight at the awesome experience).  Thanks, PJ.  The 16 Atrichopogon species that feed on the haemolymph of blister beetles have aptly been placed in a subgenus named Meloehelea.  Atrichopogon levis, aka “the grass punky” https://bugguide.net/node/view/1151920/bgimage, is a likely suspect. 

Go outside – look for bugs – look closely.

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Wooly Bear Caterpillar again

Bug o’the Week
by Kate Redmond

Wooly Bear Caterpillar again

Greetings, BugFans,

The BugLady has been doing a little dance as she walks down the trail lately, trying to avoid stepping on wooly bear caterpillars (her mission statement, after all, is “Less stepping on bugs”).  She has been less successful when she drives.  So, it’s time to rerun this episode that originally aired in 2009, but that she re-posts every five years or so.  A few new words; some new pictures:

Wooly bear caterpillars are tiger moths in the family Erebidae and in the subfamily Arctiinae.  It’s a diverse family that includes almost a thousand species of tiger, underwing, Zale, tussock moths, and more, in North America, and many more worldwide (except Antarctica).  If you have an older insect guide, tiger moths are in the family Arctiidae, but everything that was once in Arctiidae has been folded into Arctiinae.  Tiger moths are unusual in that they have an organ on their thorax that vibrates to produce ultrasonic sound.  They “vocalize” to attract mates and to defend against predators.  If you have sound-making ability, you also need “ears,” and those are on the thorax, too.  Like tigers, the adults of many species are hairy and sport bold color patches, stripes or patterns. 

Many tiger moth caterpillars are fuzzy, earning a group name of wooly bears or wooly worms (two “lls” or one “l” – take your pick.  Two lls is more common in Britain and one l is more common here).  The wooly bear du jour is the ultra-familiar rust-and-black-banded caterpillar whose grown-up name is Isabella Tiger Moth (Pyrrharctia isabella) https://bugguide.net/node/view/1937881/bgimage.  The caterpillar goes by the generic Wooly Bear, and also Black-ended Bear, and the Banded Wooly Bear.  Pyrrharctia is a “monotypic genus” – there’s only this single species in it, and they’re only found in North America. There is an amazing amount of information out there about wooly bear caterpillars, and much of it is contradictory, a problem that is exacerbated by the fact that there are many different kinds of caterpillars that are called wooly bears. 

A mature female Isabella Tiger Moth “calls” to males by emitting pheromones (chemical signals) at night, and the males zero in on her by using their sensory antennae.  Isabella Tiger Moths lay their eggs on a wide variety of plants during the warm months.  While some caterpillars are known for their picky eating, wooly bears are generalists.  They feed during the day, munching on handy, low-growing plants like grasses, “weeds” and wildflowers (cannibalism has also been reported).  Their catholic eating habits ensure that they’re constantly surrounded by food during their autumnal wandering in search of wintering sites.  

Wooly bears spend the winter as caterpillars, out of the weather under tree bark or debris, or in your garage.  Do they become “bug-cicles”?  Yes, indeed – they’ve even been found frozen in a chunk of ice.  But, like other organisms that are dormant in the dead of winter, wooly bears produce a chemical called a cryoprotectant (antifreeze) that protects living tissue against damage from freezing and thawing.  Wooly bears will stir and walk around on mild winter days and then go back into hiding when the temperatures drop again.  They wake up with the warm weather, resume eating, and pupate in late spring in a fuzzy cocoon into which they incorporate their own “setae” (hairs) https://bugguide.net/node/view/2249302/bgimage.  According to Wikipedia, Arctic summers are so short that wooly bears may need to live through several of them to become mature enough to pupate.   

One area of disagreement among references is whether the wooly bears’ wool/setae/hairs/bristles are irritants.  Having a bristly covering discourages some predators, although in the Fieldbook of Natural History, E. L. Palmer says that “skunks and a few other animals roll hairs off the caterpillars before they eat them.”  Certainly, the stiff hairs make it a harder to pick a wooly bear up, and when you do pick one up and it inevitably curls into a defensive ball, it’s pretty slippery.  Some sources say that the wooly bears’ setae contain a stinging/irritating/venomous chemical, and other sources specifically say they do not.  Still other references say the setae may cause dermatitis mechanically – that they might break off in your skin (like one of those wretched, furry cacti); and others say that that unlike many hairy caterpillars, wooly bears are harmless.  The BugLady has never suffered any ill effects from handling the familiar, rust-and-black wooly bears.

Wooly bears have been famous since Colonial times for two things: 1) their habit of crossing the roads in fall (the BugLady wonders what they crossed before the Colonists arrived and started making roads); and 2) their alleged ability to predict the weather. 

The weather lore angle was initiated by those same, road-building Colonists, who needed some forecasting done in those pre-Weather Channel days so they could figure out when to plant and harvest crops.  If its rust-colored middle band is wide, says the Almanac, the winter will be a mild one; if there’s lots of black, batten down the hatches (except for a few sources that say the opposite – that lots of rust means lots of cold).

A surprising number of scientists have felt obligated to leap in and deflate the weather story.  To them the BugLady says “Lighten up, Party Poopers, and let a little fantasy into your lives.”  They tell us that the widening middle band is a result of age, and that each time wooly bears molt, a black band becomes a rust band (except for a few who say the opposite – that rust turns to black).  So, a rustier wooly bear is an older wooly bear.  The BugLady has been curious about why the early fall wooly bears seemed more pessimistic than the later fall wooly bears and is happy to have that one resolved.  In spring, a blacker wooly bear is one that became dormant prematurely, and may indeed be telling the weather – of the previous fall.  Other research suggests that a wooly bear with lots of rust lived in dry conditions, and one source says that a wooly bear with wide black bands grew up where the habitat was wetter.  Still other scientists say that there is considerable variation in color within newly-hatched individuals from a single clutch of eggs, and that the variation persists as they age.

We have Dr. Curran, a curator of insects at the American Museum of Natural History, to thank for popularizing the wooly bear.  Charmed by the old weather saying, Dr. Curran drove north from New York City along the Hudson to Bear Mountain State Park each year for eight years in the late 1940’s and early 1950’s to measure the coloration of the wooly bears he found there.  During those years, the rusty bands predicted mild winters.  He leaked the forecasts via a friend at a NYC newspaper, and the publicity his reports generated put wooly bears on the map.  But Dr. Curran’s only real hypothesis was that Scientists Just Want to Have Fun.  He and his friends enjoyed the scenery, the foliage and the wooly bears on their annual fall forays and formed “The Original Society of the Friends of the Woolly Bear.”  Thirty years after Dr. Curran’s outings ceased, the folks at Bear Mountain State Park resurrected the Friends organization and the wooly bear count.

Wooly bears are embraced by children and adults alike, and Annual Wooly Bear Festivals are celebrated:

Clearly, Wisconsin is missing the boat, here (though Milwaukee had a third annual Wooly Bear Fest in January of 2015). 

Go outside – chart wooly bears. 

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Bugs in the News XIV

Bug o’the Week
by Kate Redmond

Bugs in the News XIV

Greetings, BugFans,

Time to chip away at the BugLady’s giant collection of insect articles.  Note that most of them are from various (free) on-line reports put out by the Smithsonian.

 

SPIDERS – We have semi-aquatic spiders around here, too.  Most, like the Six-spotted fishing spider are in the nursery web spider family – https://www.smithsonianmag.com/science-nature/these-funky-spiders-live-near-or-in-water-180984283/?utm_source=smithsoniandaily&utm_medium=email&utm_campaign=editorial&spMailingID=49766545&spUserID=ODg4Mzc3MzY0MTUyS0&spJobID=2701966506&spReportId=MjcwMTk2NjUwNgS2.  

TOOL-USING SPIDERS – Scientists get all excited when a new tool-using behavior is discovered in a mammal or bird.  Invertebrates use tools, too, like wasps that use small sticks to help excavate nest tunnels in soil, tree crickets that take advantage of curved leaves to amplify their calls, ants that soak up liquids with bits of absorbent materials to make it easier to carry the liquids back to their nests, and some beetle larvae that build a fecal shield for protection.  There’s been a good deal of discussion among scientists about what constitutes a “tool,” and some (but not all) of those definitions have included the use of other organisms.  Here’s a spider that uses a firefly: https://www.smithsonianmag.com/smart-news/these-spiders-use-captured-fireflies-as-flashing-lures-to-snare-more-prey-180984940/?utm_source=smithsoniandaily&utm_medium=email&utm_campaign=editorial&spMailingID=50099331&spUserID=ODg4Mzc3MzY0MTUyS0&spJobID=2762283843&spReportId=Mjc2MjI4Mzg0MwS2.     

ALIEN HORNETS – Not much in the news this year about the Asian murder/Northern giant hornet – the folks in the Pacific Northwest are cautiously optimistic that they’ve found all the nests.  Just when you thought it was safe to get back into the water (metaphorically speaking), along comes the Yellow-legged hornet, on the opposite coast: https://extension.psu.edu/yellow-legged-hornet

ENTOMOPHAGY (the art and science of eating insects) is gaining in popularity here, but it’s traditionally been a feature of other cuisines.  Singapore approved 16 insect species for food — https://www.smithsonianmag.com/smart-news/singapore-approves-16-insect-species-as-food-180984685/?utm_source=smithsoniandaily&utm_medium=email&utm_campaign=editorial&spMailingID=49962829&spUserID=ODg4Mzc3MzY0MTUyS0&spJobID=2741185369&spReportId=Mjc0MTE4NTM2OQS2

BUZZING BUTTERFLIES – bumble bees are famous for “buzz pollination” – causing flowers to release their protein-rich pollen by grabbing the flower parts that produce pollen (anthers) with their mandibles, disengaging their flight muscles, and vibrating their thoracic muscles mightily.  The result is not flight, but movement/shaking of the pollen-holding structures that causes pollen to rain down onto the bee.  They are aided in this by the electric charges that build up on their bodies as they fly and that attract pollen.  Can butterflies do this?  https://www.smithsonianmag.com/smart-news/static-electricity-may-help-butterflies-and-moths-pick-up-pollen-180984823/?utm_source=smithsoniandaily&utm_medium=email&utm_campaign=editorial&spMailingID=50039609&spUserID=ODg4Mzc3MzY0MTUyS0&spJobID=2760223063&spReportId=Mjc2MDIyMzA2MwS2

ANTS – Some ants produce their own pharmaceuticals:  https://www.smithsonianmag.com/smart-news/honey-made-by-ants-could-protect-against-bacteria-and-fungi-180982611/?utm_source=smithsoniandaily&utm_medium=email&utm_campaign=editorial&spMailingID=48539902&spUserID=ODg4Mzc3MzY0MTUyS0&spJobID=2503571888&spReportId=MjUwMzU3MTg4OAS2

CLIMATE CHANGE – WHAT COULD POSSIBLY GO WRONG? – https://www.smithsonianmag.com/smart-news/rash-causing-moths-are-spreading-because-of-climate-change-180979650/?utm_source=smithsoniandaily&utm_medium=email&utm_campaign=20220228-daily-responsive&spMailingID=46470006&spUserID=ODg4Mzc3MzY0MTUyS0&spJobID=2200009908&spReportId=MjIwMDAwOTkwOAS2.

UP CLOSE AND PERSONAL – As seasoned BugFans know, the BugLady is a big fan of macro/extreme macro/scanning electron microscope (SEM) photography.  Enjoy:  https://www.smithsonianmag.com/science-nature/these-stunning-portraits-of-insects-reveal-the-intricacies-of-an-amazing-world-180984926/?utm_source=smithsoniandaily&utm_medium=email&utm_campaign=editorial&spMailingID=50122698&spUserID=ODg4Mzc3MzY0MTUyS0&spJobID=2763062134&spReportId=Mjc2MzA2MjEzNAS2

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Little Yellow Butterfly

Bug o’the Week
by Kate Redmond

Little Yellow Butterfly

Howdy, BugFans,

When the BugLady was on the trail recently, a small, yellow butterfly flew by, just above the ground.  It was noticeably smaller than the ubiquitous Orange and Clouded Sulphurs, but it zipped out of sight pretty fast.  Mike Reese, host of the excellent Wisconsin Butterflies website (https://wisconsinbutterflies.org/) describes similar experiences “It has not been the easiest butterfly for me to observe. I have seen this butterfly in central Wisconsin several years and have attempted to photograph it. All the individuals I saw took off on a beeline for other areas, dancing calmly but surely away from me, never to be seen again.”  Fortunately, the BugLady’s butterfly turned around, came back, and posed nicely.

It was a Little Yellow/Little Sulphur/Lisa Yellow (Pyristia lisa) (formerly Eurema lisa).  Like the larger Sulphurs and the “Whites,” it’s in the family Pieridae.  Its wingspread measures 1 ¼” to 1 ¾” (females are slightly larger than males, but otherwise males and females are very similar), and there are pale and dark forms, depending on the time of summer https://bugguide.net/node/view/1752987/bgimage, https://bugguide.net/node/view/898574/bgimage.  The BugLady’s butterfly snapped its wings shut immediately; here’s one with wings open https://bugguide.net/node/view/1184957/bgimage

Little Yellows are southern butterflies, abundant in grasslands, open areas and along woodland and road edges and railroad tracks as far south as Central America and Costa Rica, but they migrate north in summer and are found from the Great Plains as far west as New Mexico and South Dakota, to the Atlantic Coast as far north as Canada.  Their numbers in Wisconsin vary from year to year, and they may persist into October here, but the final generation of the summer turns around and heads back south again. 

Males keep an eye out for females, and when they see one, they court by touching her with their legs and wings.  The female responds by spreading her antennae so she can sense his pheromones.  If she’s not interested, she flutters her wings or departs; if she is – https://bugguide.net/node/view/2299141/bgimage.

She lays her eggs on the midveins of the leaves of a host plant, and when the eggs hatch, the larvae feed on the tender leaf tissue between the veins, resting along the midrib (nice series of pictures https://bugguide.net/node/view/1036429).  Adults live a brief 10 days.   

Little Yellows may produce five generations in their southern breeding range, and those that reach Wisconsin and beyond will breed if they can find host plants, but they are too sensitive to the cold to survive winters above 40 degrees north latitude (Philadelphia, PA to Columbus, OH to Boulder, CO).

Most sources only list a few caterpillar host plants in the Pea/Legume family, specifically Partridge Pea, Wild Senna, and Mimosa strigulosa, a small mimosa shrub.  Ebner, in his Butterflies of Wisconsin (1970), writes that clovers in the genus Trifolium are undoubtedly used as host plants by the Wisconsin populations.  The butterflies nectar on aster and goldenrod, and crowds of males gather at the edge of puddles to sip minerals from the damp earth https://bugguide.net/node/view/432629/bgimage.  Little Yellows are preyed on by crab spiders and ambush bugs and in the south, native praying mantises.

Little Yellows are small but mighty – they’re famous for mass migrations that take them far from home.  In 1874, Samuel Scudder described a swarm that reached the Bermuda Islands, “Early in the morning, several persons living on the north side of the island perceived, as they thought, a cloud coming over from the northwest, which drew nearer and nearer to shore, on reaching which it divided into two parts, one of which went eastward and the other westward, gradually falling upon the land.  They were not long in ascertaining that what they had taken for a cloud was an immense concourse of small yellow butterflies, which flitted about all the open, grassy surfaces in a lazy manner, as if fatigued after their long voyage over the deep.  Fishermen out near the reefs, some miles to the north of the islands very early that morning, stated that numbers of these insects fell upon their boats, literally covering them.” 

Magic.

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Rough Stink Bug

Bug o’the Week
by Kate Redmond

Rough Stink Bug

Greetings, BugFans,

The BugLady has a thing for stink bugs.  They’re like bumble bees and water lilies – she can’t walk past one without taking its picture.  She especially likes stink bugs in the genus Brochymena, the Rough stink bugs, which look like walking fossils.  But before we talk about the Brochymena, which have made a few brief appearances in BOTW, here’s a brief Stink Bug 101:

Stink bugs are in the family Pentatomidae, which means “five sections” and refers to the number of segments in the antennae.  In the UK, they’re called shield bugs, a name that is applied here casually to members of the Pentatomidae, and more specifically to members of a different family.  About 220 of the globe’s 5,000 stink bug species live in North America.

“Stink bug” because they are chemically defended – when alarmed, they can release a lingering odor that may be unpleasant (or not), noxious, or even toxic (think “cyanide”).  As a defense against predators, the odor is imperfect.  Most birds have no sense of smell, but a smaller predator that got a face full of chemical spray would be deterred, and some parasitic wasps and flies actually locate stink bugs by their odor. . 

And, of course, common names being what they are, the name can and is applied to any unrelated insect that has an odor.

Many stink bugs are plant feeders (some damage agricultural crops), and others are carnivores that help to control unwanted insects.  And some, in cuisines around the world, are prized for the spiciness they add to a dish.  All feed by poking their piercing-sucking mouthparts into their food of choice and injecting a saliva that predigests tissue so it can be siphoned up.

Most stink bugs come in utilitarian greens, grays, or browns, but some come in pretty flashy colors https://bugguide.net/node/view/531728/bgpage, especially as nymphs https://bugguide.net/node/view/344542/bgpage.

A few species of stink bugs exhibit maternal care – https://bugguide.net/node/view/1329274/bgimage.   

ROUGH/TREE/ARBOREAL STINK BUGS – Brochymena – are one genus (with 17 species) of one tribe (Halvini) of one subfamily (Pentatominae) of the stink bug family.  Based on images they’ve received from their community, bugguide.net shows the Brochymena occurring from sea to shining sea, except North Dakota and Manitoba, and their range extends south into Panama.  They’re typically found on trees and shrubs.   

They’re typically found on trees and shrubs, but their cryptic colors and textures can make them difficult to find because they look like a bit of bark or lichen on six legs.  At about 5/8”, they’re large for stink bugs. 

For the Brochymena, everything was going swimmingly until 1998, when a new stink bug came to town.  It was the Brown marmorated stink bug https://bugguide.net/node/view/2232265/bgimage, which is a huge pest in orchards and agricultural fields and, in the winter, in homes.  The two look similar – the BMSB has wide pale bands on its antennae and one white band on its hind legs; while the Brochymena have two white bands on their hind legs, a protruding, square/pointy face with antennae noticeably in front of their eyes, and toothed “shoulder pads” that look like a bit of cog wheel.  If you see a lot of them, they’re BMSBs. 

There’s some discussion about their diet.  Bugguide.net says that they are “Phytophagous [plant-eating] (some reports of predation).”  They’re known to feed on the sap and leaves and seeds of many species of trees and shrubs including ash, willow, and box elder, with brief, opportunistic forays into carnivory.  Unlike many other species of stink bug, they’re not considered harmful, and because they’re not considered pests, they haven’t been exhaustively studied.  Other sources say that their forays into carnivory are more than occasional, and that they eat caterpillars, leaf beetle larvae, aphids, and other soft-bodied insects that they come across. 

A Rough stink bug’s “stink” – said by one source to smell like maraschino cherries, and by another, like almonds – may not deter ants, tachinid flies, sand wasps, and a variety of birds (especially vireos, says one source).  Eric Eaton, in his Bug Eric blog, writes that “Given their cryptic nature, it amazes me that any other creature could find them and make a meal out of them.”  He continues, “Feather-legged flies in the genus Trichopoda glue their eggs to the top of the stink bug’s body, where the insect cannot reach to groom them off.  The fly larva that hatches bores through the exoskeleton of the host and feeds as an internal parasite, usually killing the bug eventually.” 

Adult Brochymena overwinter, sheltered in leaf litter, mulch, bark crevices or logs (some pick stacks of firewood, and are then brought inside in winter), and they’re sometimes seen out and about on warm winter days.  They emerge to mate in late spring, and females lay eggs in clusters of 10 to 20 on twigs.  Adults die by the end of June, and nymphs are found throughout summer.  There’s only one brood a year.

Eggs
Nymphs

Isn’t this “probably unnamed” Arizona species a beauty https://bugguide.net/node/view/2355448/bgpage!

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – The End of Summer

Bug o’the Week
by Kate Redmond

The End of Summer

Howdy, BugFans,

We’ve arrived at the final act in this summer’s insect drama – a drama played out over the months by an ever-changing cast of characters.  Some are regulars, with successive generations appearing in multiple acts throughout the season, while others step in for only one act of the play.  Here are some of the actors that appeared on stage after mid-August.

DARNER WITH SPIDER – well, the darner migration was nothing short of magical this year, and then it was over.  And then it restarted – lots of Common Green Darners in the air on September 19 and 20, along with a bunch of Black Saddlebags.  They’re heading south along the lakeshore, aiming for the Gulf States, but they don’t all make it.  The BugLady’s guess is that this one was perched in the grass, and when it took off, it ran into the web of an orbweaver.  It messed up the web, but because it wasn’t flying at full power, the spider was able to snag it.  THANKS to the family that located this tableaux along the trail and pointed the BugLady at it.

TIGER SWALLOWTAIL – perfection on the wing, but far too few of them this summer.

GOLD-MARKED THREAD-WAISTED WASPS (Eremnophila) put the “thread” in the Thread-waisted wasp family (Sphecidae).  They’re solitary wasps that dig single-celled egg chambers in the ground and provision them with caterpillars of sphinx or owlet moths (and the odd of skipper butterfly caterpillar).  Her long legs allow her to straddle a larger caterpillar and walk it back to her nest https://bugguide.net/node/view/1408944/bgimage.  She keeps her strength up by sipping carb-rich flower nectar.

RED-LEGGED GRASSHOPPERS making more Red-legged grasshoppers.  ‘Tis the season.  

GRAY HAIRSTREAKS are listed as the most common hairstreak in North America (because their caterpillars are “catholic” eaters that feed on about 200 different plants), but they’re not common in Wisconsin.  

Fun facts about Gray Hairstreaks:

  1. The point of the eyespot and the “tail” is to make the butterfly’s rear end look like a front end, with eye and “antenna,” thus confusing predators;
  2. Gray hairstreak caterpillars are tended by ants in return for honeydew (produced, of course, in the caterpillar’s “honey gland”);
  3. Both the caterpillar and the pupa produce sound.

TREE CRICKET – the voice of the prairie in late summer and early fall.  This one is (probably) in the Oecanthus nigricornis group, maybe the Forbes tree cricket https://www.listeningtoinsects.com/tree-cricket-introduction

BIG SAND TIGER BEETLES are all about sand.  Their eggs are buried in the sand; their larvae https://bugguide.net/node/view/1277687/bgimage dig long tunnels in the sand and then pop out when unwary insects and spiders wander by.  At up to six feet long, the tunnel extends below the frost line and allows them to survive the winter.  Adults stand “on tiptoe” (stilting) to raise themselves incrementally higher off the hot sand.  Not surprisingly, Tiger beetles have fan clubs.

FIERY SKIPPER – these beautiful, inch-long, golden butterflies aren’t from around here, though they regularly visit God’s Country and beyond.  Their usual range is southern and even tropical, and they move north in mid-summer and produce a brood here, but it’s too cold for them to overwinter (for now).  They’ve made it to Hawaii and are unwelcome there, because their caterpillars feed on grasses. 

EUROPEAN PAPER WASPS are buzzing around the hawk tower these warm, sunny days, so the BugLady has to look sharp before she puts her hands on the railings.  Fortunately, they are jumpy wasps that usually spot her before she gets too close.  They arrived on the East Coast 40 or 50 years ago and have spread across the northern US and Canada.  They catch, masticate, and regurgitate caterpillars and other small insects for their larvae.  The lovely gold legs and antennae separate them from our common Northern paper wasp.

Fun facts about European paper wasps:

1)    The brighter the coloration of a female European paper wasp, the more toxic her sting is;

2)    Females with more spots on their faces are dominant.

FAMILIAR BLUETS – Big and startlingly blue, Familiar Bluets are one of the last damselflies on the scene.  (‘Tis the season.)

Caterpillars of VIRGINIAN TIGER MOTHS are also known as Yellow wooly bears or Yellow bear caterpillars (though they come in white, yellow, caramel, and rusty colors, and here’s a pink one https://bugguide.net/node/view/1728143/bgimage).  They’re food generalists, and so are all over the place (not just in Virginia).  Although some people are sensitive to their hairs, the hairs are not poisonous.  Adults are spectacularly white https://bugguide.net/node/view/1984450/bgimage, but when they are alarmed, they curl their abdomen to flash a startling orange https://bugguide.net/node/view/2329153/bgimage.   

NURSERYWEB SPIDERS carry their egg sac around in their jaws (wolf spiders carry theirs aft) and when the eggs are close to hatching, she creates a loose “nursery web,” installs the egg sac in it (hers was on the underside of the leaf), and then guards it until the eggs hatch and the spiderlings have molted once.  No help from Dad – if she doesn’t eat him (sexual cannibalism – an important nutrient booster) (he wraps her legs with silk during courtship to try to prevent this), he leaves to pursue other relationships.  He gives her a “nuptial gift” of a silk-wrapped prey item at the start of courtship so that she will think well of him, but after he has immobilized her and exchanged bodily fluids, he takes the gift with him when he goes. 

CRANE FLY – the “Old Wives” really got it wrong about Crane flies.  Though they’re also called “mosquito hawks,” they do not eat mosquitos (or any meat of any kind).  They do not bite anything at all, but they’re reputed to be the “most venomous insects in the world.”  The confusion may have come because of their resemblance to the cellar spiders, themselves getting a bad rap because their bites are practically harmless.  They’re just a short-lived fly whose larvae inhabit a variety of habitats from wetlands to lawns (where they both feed on and fertilize the grass).

EASTERN TAILED-BLUES are tiny butterflies with wingspans of an inch or less, but they’re tough enough to fly well into fall (four years ago, the BugLady saw one on November 4).  Like the Gray Hairstreak, the eye and tail on the hind wing are there to trick hungry birds into grabbing a wing, not an abdomen.  ‘Tis the season.

Go outside – there are still bugs!

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Zebra Jumping Spider

Bug o’the Week
by Kate Redmond

Zebra Jumping Spider

Greetings, BugFans,

The BugLady was moseying around her cottage, photographing doodlebug digs, when she spotted this very small (maybe ¼”) jumping spider with its prey.  It was on a sunny, south-facing wall – right where it was supposed to be!

Zebra spiders, aka Zebra jumpers (Salticus scenicus) are in the family Salticidae, the Jumping spiders.  Salticus is Latin for “dancing,” and scenicus is Greek for “theatrical” or “of a decorative place,” and refers to the spider’s flashy colors, which can look iridescent in the right light.  Thanks to BugFan Mike, as always, for the ID.  

We’re on a roll here, having recently introduced the non-native Clover weevil and the (probably) non-native American Copper butterfly.  The Zebra spider’s original range included Europe and western Asia.  It was first collected in North America (in Illinois) in 1933, and now it occupies most of the northern two-thirds of North America.  It’s an urban spider that loves the sun-warmed sides of buildings, but it’s also found away from human habitation, on bare rocks.

There’s some variation in pattern and color, and spiders that live in polluted urban areas may be all black.  Here’s a side view https://bugguide.net/node/view/1339892/bgimage.  Males have large, black jaws called chelicerae https://bugguide.net/node/view/2251820/bgimage.  Like all jumping spiders, Zebra spiders have appealing (some say cute) faces https://bugguide.net/node/view/171573/bgimage – jumping spiders have fan clubs and Facebook pages, largely because of the size and arrangement of their eyes. 

Jumping spiders have eight eyes, four facing forward and four facing upwards – they have depth perception, can judge distances, and can see in color.  Research suggests that when the lateral eyes on each side of those big median eyes pick up motion, they tell the median eyes where to look.  The four eyes on top of the head (cephalothorax) sense movement (helpful for dodging predators) and light. 

Zebra spiders don’t spin for their supper, they jump (and they can jump as far as four inches).  They stalk their prey brazenly by creeping directly at it, but if their prey is much larger than they are, they sneak up from behind.  Either way, they attach a silken drag line to the substrate as they leap, in case they miss or in case they and their prey tumble over the edge.  They bite, subdue, and eat their prey on the spot – they don’t wrap and store it because they have no web to store it in.  

What do they eat?  Various kinds of flies, including mosquitoes, are favorites https://bugguide.net/node/view/1811146/bgimage, but they go after insects that are much larger than they are https://bugguide.net/node/view/228175/bgimage and https://bugguide.net/node/view/383371/bgimage.  They find ants distasteful, but they will eat their fellow spiders https://bugguide.net/node/view/284184/bgimage.  

Females attract wandering males with pheromones, and courtship is visual – males dance, and the best dancers win.  Faint heart ne’er won fair maid.  He waves his front legs and chelicerae and displays his patterned abdomen (so that she doesn’t think he’s prey).  If she’s impressed (and scientists don’t know exactly which moves will light her fire), she’ll crouch and let him approach.  Sometimes males mistakenly display in front of other males, which results in ritualized battles that are won by the most aggressive fighter.

She produces a silken sac that holds 15 to 20 eggs and hides it under leaves or debris, and she guards it until the eggs have hatched https://bugguide.net/node/view/236348/bgimage.  The spiderlings stay with her until after their second molt, and then they disperse.  They overwinter as almost-mature spiders and may live for a year or two. 

Fun Facts about Zebra Spiders:

1)    Their jumps are driven not by muscles, but by hydraulic pressure – the spider increases the pressure of its haemolymph (blood), and that causes the 4th set of legs to straighten, which propels it off the ground.  The fact that the spines on a spider’s leg stand up as its legs straighten is considered proof of that explanation.

2)    Zebra and other jumping spiders can abseil/rappel down walls and rock faces.

3)    Cushions of hairs on the bottoms of their feet have adhesive qualities and allow them to walk on smooth, vertical surfaces. 

4)    Zebra jumpers operate during the day, and they retreat into silk shelters spun in crevices and under leaves and bark by night. 

5)    Vibrations (like buzzing wings) help Jumping spiders recognize their prey.

6)    If a Zebra spider accidentally comes inside, it might take up residence in the corner of a window.  No – it can’t bite us – not even a little bit.erved by a large jumping spider that was inside the car as she drove, alternately staring at her (jumping spiders are good at that) and then disappearing as she drove (that, too).

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

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