Author: rbuchholz

Salutations, BugFans,

The BugLady is literally surrounded by Cross orbweavers (Araneus diadematus).  Egg cases were attached to the house and porch last fall, and masses of spiderlings emerged in early summer; she often has to break through a web to get out the door.  In her research, the BugLady has seen this group labeled as orbweavers, orb-weavers, and orb weavers, even within the scientific community; she’ll use “orbweavers” because it annoys Spellcheck).

They’re called orbweavers (family Araneidae) because the webs they spin are the classic, round, flat webs that we learn about as kids.  You know – Charlotte’s people.  Bugguide.net tells us that “All orb weavers spin some sort of web consisting of concentric circles (smaller circles within larger circles) with “spokes” radially going from the center outwards toward the anchor points (https://bugguide.net/node/view/1000727/bgimage) …. Most orb weaver webs are vertical (perpendicular to the ground), but there are a handful that will spin a horizontal web (parallel to the ground). Some of the webs can be extremely large (over 3 feet in diameter)” (a few webs on the BugLady’s porch have approached that size; and lately, the BugLady has had fun luring mosquitoes into them, which the large female seems to eat directly without wrapping and storing.  Hors d oeuvres).

Speaking of which, spiders are carnivores, right?  Well… mostly.  Researchers Eggs and Sanders noted in a paper in the journal PLOS that when orbweavers, including Cross orbweavers, recycle (eat) old webs, they also consume pollen and fungal spores that have stuck to the strands.  And they do it on purpose – some pollen grains are too large to “swallow” casually and have to be pre-softened externally by enzymes, just like animal prey.  They reckoned that about 25% of the diet of juvenile orbweavers is pollen.

Cross Orbweavers were mentioned briefly in a 2012 BOTW about several species of large orbweavers.  For basic information about the group, see https://uwm.edu/field-station/big-orb-weaving-spiders/.

The Cross orbweaver’s range is described as “Holarctic,” which means that it’s found in northern areas of the New World (where’s it’s an immigrant) and of the Old.  In the New World, it’s found in southern Canada and across the United States from New Jersey to northern California.  With a range like that, it’s picked up a bunch of common names, among them European garden spider, house spider, diadem spider, cross spider, pumpkin spider (a name shared by the Marbled orbweaver) and crowned orb weaver.  It’s a well-known species (because it likes people and their habitations, especially if those habitations have exterior lighting) and a well-studied one.

As is the case with most species of large orbweavers, there can be considerable color variation (and dark individuals may get lighter in color as they age), and not all of them have an obvious “cross” on the top of the abdomen, and sometimes a microscopic examination is required to make an ID https://bugguide.net/node/view/1296471/bgimage, https://bugguide.net/node/view/1444765/bgimage, https://bugguide.net/node/view/1458037/bgimage, https://bugguide.net/node/view/1344384/bgimage, https://bugguide.net/node/view/1331634/bgimage, https://bugguide.net/node/view/713309/bgimage; and http://spaceweathergallery.com/indiv_upload.php?upload_id=148031&PHPSESSID=63o1fc8cg5takrhq187eemo2a6 (OK, the BugLady threw that in because the Aurora season is heating up and www.spaceweather.com’s “Realtime Aurora Photo Gallery” takes us there).  Males aren’t dramatically smaller than females (about 6-13mm long, to the females’ 6-20mm), but females have a rounder abdomen, especially now, when they’re gravid.

They hatch in spring, stay together until their first molt (the collective noun for spiders is a “cluster” or “clutter”), and then scatter, and spiderlings that were tiny in June have reached lunker size now, at the end of their lives.  In late summer, mature males may “adopt” immature females in hopes of a future liaison.  A male approaches a female cautiously, with lots of advance-and-retreat, and tentative touching; she is bigger and hungrier than he is, and she may have a different definition of “romantic dinner.”  In any case, males don’t survive long after mating, and yes, she may eat him.  She produces and hides an egg sac that contains as many as 800 eggs and is almost as big as she is (see the series of pictures at https://bugguide.net/node/view/719111/bgimage), and she hangs around to guard it for the rest of her life.  The first killing frost finishes off any survivors (interestingly, Cross orbweavers have a two-year life cycle in Europe)

Scientists have, indeed, studied the heck out of Cross orbweavers.  They’ve looked at the complex business of web-building, at the factors that affect the placement/angle of the radius threads (spokes), at specifications for habitat selection, at the types/functions of hairs on the spiders’ legs, at the fact that urban spiders are larger than their rural relatives (the urban heat island effect), at the tensile strength of cocoon silk, and much more.  Be sure to check the web diagrams in this study https://www.sciencealert.com/spider-on-drugs, in which researchers dosed Cross orbweavers with a variety of substances – LSD, caffeine, pot, mescaline/peyote, and a few more (with a link to a longer NY Times article).

Fun Cross Spider Facts:

• Cross orbweavers typically hang upside down at the center (hub) if their web.  Eric Eaton describes their behavior when alarmed, “The spiders themselves will literally shake at the close approach of a person or other large animal, vibrating their web and no doubt startling the inquisitive visitor. Should that tactic fail, most orb weavers drop abruptly from their web, anchoring a dragline to the hub so that they can climb back up once danger passes” (Bug Eric http://bugeric.blogspot.com/2011/08/spider-sunday-cross-spider.html).

• Cross orbweavers are one of the best-known spiders in the world and in 2010 had the honor of being named “European Spider of the Year.”

• Eric Eaton also tells us that ““Anita” and “Arabella” were two female Cross spiders that were sent into space in Skylab 3 in 1973 to study the effects of zero gravity on web construction.”

Cross orbweavers are not aggressive and generally bite only if cornered or inadvertently grabbed.  Side effects of their bites are mild in most people (redness, swelling, pain) and last only a few days.

Kate Redmond, The BugLady

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

Salutations, BugFans,

The BugLady was walking along the trail at Forest Beach Migratory Preserve recently when she saw a flashy, orange, inch-long wasp actively hunting for something in some white ash saplings.  The wasp was flying from tree to tree, searching among the leaves.  It returned several times to a twig upon which sat an infant Tiger swallowtail caterpillar, and the BugLady feared that the wasp would grab the caterpillar to provision a brood cell; but it turned out that this was an Ichneumon wasp, and she had other plans for the caterpillar.

The wasp family Ichneumonidae is a huge one – at around 60,000 known species (and maybe another 40,000 undiscovered species waiting in the wings), it’s in contention with weevils and rove beetles for the title of Largest Animal Family.  Some 5,000 species of Ichneumons call North America home, and about them bugguide.net says, “Ichneumonids are notoriously hard to identify: aside from the sheer number of species, there are numerous cases of distant relatives that appear almost identical. Any identification based solely on comparing images should be treated as suspect unless an expert has said there are no lookalikes for the species or group in question.” Which puts the BugLady way out on that taxonomic limb again, but she’s gotten pretty comfy there.

Ichneumon larvae typically live as parasitoids in the bodies of other invertebrates, not delivering the coup de grace until it’s time to pupate (the wasp larva successfully; the host, not).  Ichneumons can be highly specific in their choice of hosts.

So, the orange wasp is (probably) Trogus pennator (no common name).  Here’s a nice picture of one: https://bugguide.net/node/view/961275/bgimage.  Trogus comes from a Greek word meaning “to gnaw” and pennatorfrom the Latin for “feather” or “wing.”  And yes, there is a look-alike, an unrelated spider wasp named Tachypompilus ferrugineus, but Tachypompilus has a smooth-ish abdomen https://bugguide.net/node/view/128288/bgimage, and Trogus’s abdomen has a “beaded” look.  It has been suggested that Trogus pennator mimics the spider wasp because spider wasps can sting (painfully), while the Kaufman Field Guide to Insects of North America, says of Trogus’s subfamily Ichneumoninae that “Females have venom glands and some can sting weakly.”  There are a dozen species in the genus, half of them in the New World.

Credit where credit’s due – a good deal of the work that has been done on Trogus pennator has been carried out by researcher Karen Sime of Cornell University (Go, Big Red!), who theorizes that the genus originated in the Palearctic region (the northern half of the Old World) and arrived in the New World via Alaska on the heels of the spectacular Old World Swallowtail butterfly https://bugguide.net/node/view/1199312/bgimage.

Why?  Follow the Food!  The larvae of Trogus wasps are (alas) parasitoids of the larvae of swallowtail butterflies.  Some species of Trogus are swallowtail generalists, and others are pickier, but they all avoid the caterpillars of the Pipevine swallowtail, whose host plant’s toxicity the caterpillars stockpile.  How do the wasps know?  They “sample” the caterpillar with their antennae, which alerts them to the presence of poisons.

So Ms. Wasp’s search was for swallowtail caterpillars, and a lot of research centers on exactly how she locates them.  It’s possible that the wasp can identify the host plants visually, and she may be able pick up on the chemical signature of undamaged leaves, but in one study, Trogus pennator wasps targeting Zebra swallowtail larvae were found to recognize the odor that a host leaf emits when it’s damaged by grazing caterpillars.  Once they’ve found caterpillars on them, “naive wasps” quickly learn their host plants.  After that, they don’t waste time on non-host plants, and they concentrate on host plants with damaged leaves.  But – think about it – does a wasp like Trogus pennator, which has more catholic tastes, learn to ID all of the host plants of Tiger Swallowtails (Butterflies of the North Woods lists about a dozen of them) plus the food plants of Black Swallowtails (here’s one that emerged from a Black Swallowtail chrysalis https://bugguide.net/node/view/395314), plus Zebra Swallowtails, plus….?

When she finds a caterpillar, Trogus pennator inserts a single egg into it (and the BugLady may have accidentally captured that moment).  The BugLady found a second caterpillar, in the open on the leaf of a nearby ash – it had a small, black “button” at the end of its abdomen, and the BugLady is wondering about that.  The caterpillar goes on its way, feeding and growing, but it’s a goner – only the wasp will exit the chrysalis.  If the swallowtail caterpillar is from the second brood, destined to overwinter as a chrysalis, the wasp larva goes into a state of diapause (suspended animation) along with it and emerges in spring.

Some swallowtails try to adapt – butterflies may lay eggs lower on host plants than the wasps typically hunt, and caterpillars may feed at night.

[Editorial Comment: She’s a beautiful wasp, and her behaviors are fascinating, and yes, she has to make a living, but Tiger Swallowtails?  Tiger Swallowtails are the BugLady’s favorite bug, and she’s worried about them.  They have two broods a year – the small spring flight is made up of survivors of the cohort of fall caterpillars that endured the rigors of winter as a chrysalis.  Their offspring pupate in the mild days of June and July and emerge as a mid-to-late summer brood that needs to be large, because of the hazards their offspring will face in the winter.  The spring numbers were respectable this year, but the wildflowers are waning, and the BugLady just hasn’t seen many second brood Tiger Swallowtails.  Some other phenological benchmarks seem a bit off kilter this summer, so maybe there’s still time.]

Kate Redmond, The BugLady 

P.S. – this seems timely: https://uwm.edu/field-station/the-mighty-mosquito/

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

Greetings, BugFans,

OK – it’s September, but the bug season isn’t over yet.

Outside of wetlands, if there’s anything better than a walk on the prairie, surrounded by Big Bluestem grass, with big Common Green Darners and Black Saddlebags dragonflies overhead, the BugLady hasn’t found it yet.  Here is another batch of summer images, mostly from prairies.

Look for the AMERICAN RUBYSPOT (one of our classiest damselflies) near running water.  Yes, the male is spectacular, but the female is no slouch, either.

ANT AND GRASSHOPPER – When Aesop wrote the fable about the grasshopper and the ant (you remember it – the ant prepares for tomorrow while the grasshopper fritters), this probably wasn’t what he had in mind.  The largish ant and the smallish grasshopper were going home for dinner together.

CAROLINA LOCUST – This is the large, very well camouflaged grasshopper/locust that jumps up in front of you as you walk in the prairie.  Its flying wings are inky, with cream-colored margins, reminiscent of a Mourning Cloak butterfly.  Males advertise for mates by hovering above the grass-tops and making a rattling/crackling/snapping/clicking sound (it’s called crepitation) with their wings.  It looks like it was carved out of stone.

BLACK SADDLEBAGS DRAGONFLY – Any day now, Black Saddlebags and Common Green Darners will set their course for the South and sail down the Lake Michigan coastline in a steady stream.  Only 15 of the 460+ species of dragonflies and damselflies migrate, and it’s a grand sight.  Local BugFans can watch from the bluffs at Lion’s Den Nature Preserve near Grafton as the dragonflies go past at eye level.

Mooned by JAPANESE BEETLES.  They’re having a good year this year.  These lusty scarabs were first seen in 1916 at a plant nursery in New Jersey, having arrived as hitchhikers in a shipment of iris bulbs from Asia.  They are the ultimate generalist herbivores, feeding on the leaves and fruits of about 300 different plant species, both woody and herbaceous.  Pretty, though.

MAYFLY – The BugLady was photographing an ambush bug with its prey when she felt something land ever-so-lightly on her arm.  If she’d have guessed before looking, she never would have guessed a mayfly.  Mayflies are in the well-named order Ephemerata, and ephemeral they are.  Their naiads live for a year under water, and when they emerge as adults, often in Biblical numbers, they are unequipped with mouthparts and live for only a few days.  But it’s enough.

BLACK AND YELLOW ARGIOPE – The BugLady is thrilled to see good numbers of these spectacular orbweavers this year.  They’re beautiful, and they’ve been hard to find lately.  Orbweavers are with us all summer, mostly unobserved until late August, when they reach an impressive size.

STINKBUG AND PREY – A (probably) Podisus maculiventris stinkbug nymph making a meal out of an alien Pine sawfly larva, on a porch rail; the duo probably dropped out of the White pine above.  They’re known as Spined soldier bugs because of the adults’ pointy “shoulders” https://bugguide.net/node/view/700220.  Stinkbugs insert their mouthparts into their prey, pump in the meat tenderizer, wait a bit, and then suck out their prey’s softened innards.

TIGER SWALLOWTAIL – The BugLady has a small flower garden at her new home, mostly populated by horticultural (“tame”) stuff that she’ll be replacing with native plants.  She may make an exception for this lily, which was both hummingbird and butterfly-friendly.

VICEROY and MONARCH – Telling a Monarch butterfly from a Viceroy is easy, once you know the secret handshake.  Viceroys are a bit smaller, and (to the BugLady’s eyes) their flight is a bit peppier than a Monarch’s, but those traits are pretty subjective.  The Viceroy is always held up as a Monarch mimic that cashes in on the fact that Monarchs are toxic because of their caterpillar’s food plant, and predators learn to avoid them.  Viceroy caterpillar host plants are willow, aspen, and poplar, and some scientists believe that while they may not be toxic, they are probably distasteful, and the two species complement each other https://uwm.edu/field-station/viceroy/.  Anyway, the Viceroy, on the left, has a C-shaped black line through the hind wing.

SYRPHID/HOVER/FLOWER FLIES – There have been astonishing numbers of these small, harmless, bee-mimicking flies in grasslands lately.  Swallows, dragonflies, damselflies and other consumers must be living large on them.

A MASS of MONARCHS – Monarchs migrate along the lakeshore, too.  The BugLady found two groups with about 50 Monarchs apiece – early migrants – tucking themselves in for the night at the end of her driveway one afternoon in mid-August.

Go outside.  Find a prairie.  Look at bugs.

Kate Redmond, The BugLady

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

Howdy, BugFans,

The BugLady had a wonderful Beetle Experience the other day.  She was at Riveredge Nature Center, attempting to photograph some butterflies (a Common Wood Nymph and a few Viceroys) on a large cup-plant that had bloomed and was forming seeds when she noticed s

ome drab, half-inch, hairy bees sitting on/in the flower heads.  When she took a closer look (and some pictures, of course), she discovered that they were a flower scarab called the Bumble Flower Beetle.

(Blogger Dragonfly Woman got pretty excited, too, when she saw her first one: “It wasn’t a bee at all, but Euphoria, a fantastic scarab beetle! It tried to fly away when I picked it up, making a loud buzzing reminiscent of its namesake as it attempted to escape, but I snatched it out of the air and slipped it into my lunch bag to take it home to photograph. https://thedragonflywoman.com/2013/04/12/views-of-euphoria/.)

Flower scarabs are in the beetle family Scarabaeidae and the subfamily Cetoniinae.  As a group, the 4,000 or so flower scarabs/flower chafers are diurnal as adults, feeding on pollen and nectar (and providing pollination services while they’re at it), or on sap drips on injured plants, or on plant tissue, including fruit.  Their larvae are recyclers, mostly eating decaying vegetable material.

The larvae of some species in the subfamily grow up in ant hills, consuming the ants’ food stores while the ants inexplicably ignore them.  Adult beetles may live there, too, secreting a sweet liquid for the ants to eat while the beetles eat larval ants (fascinating back story – some adult beetles are “killed” by ants (they play dead) and are carried down into the nest).  A California species of Euphoria lives on the midden heaps in pack rat burrows.  See http://bugeric.blogspot.com/2015/04/anteater-scarab-beetles.html for an account of the lifestyle of a related beetle.

Some genus members run afoul of agriculturalists and are well-known to University Extension entomologists across their range, but a few may be taking the rap for other insects.

Anyway, the excellently-named Bumble Flower Beetle (Euphoria inda), also called the Brown Fruit Chafer and the Indian Cetonia, is one of 24 Euphorias in North America.  Here’s a glamour shot https://bugguide.net/node/view/987232/bgimage.  Its name comes from both its appearance and its behavior.  The beetles happily congregate, and they may fly around near the ground like bees.  While most beetles fly with their elytra (the hardened, protective front set of wings) extended, the chafers fly with elytra closed, producing a buzzy sound https://books.google.com/books?id=IhLZDgAAQBAJ&pg=PA40&lpg=PA40&dq=flower+chafer+beetles+closed+elytra&source=bl&ots=lpvDoVMBpV&sig=SWIAOqvVCZ0-RPXp8sxJaPKU1Zk&hl=en&sa=X&ved=2ahUKEwjX2oakk4fdAhXm8YMKHT-5BGc4ChDoATACegQICRAB#v=onepage&q=flower%20chafer%20beetles%20closed%20elytra&f=false).  It’s speculated that the two-winged mode may allow more agile flight.

Bumble flower beetles can be found in grasslands and gardens across the continent, feeding on fermenting sap, ripe/rotting fruit, flowers, pollen and nectar.  It’s believed that they take advantage of already-existing cracks and splits in fruits and of damage done by other insects and that they don’t spread plant diseases while feeding.

They are sometimes listed as minor corn pests.  Said F. M. Webster in his “Insects Affecting the Corn Crop” in the 1886 report of the Indiana Board of Agriculture, “The adult beetle has been accused of feeding upon the kernels of young corn in the fields, and Dr. Harris states that they sometimes feed upon the sap of the stalks in September.  Its depredations have so far been of minor importance, and, in fact, it is not altogether clear that the insect is guilty of making the first attack upon the corn, there seeming to be the strong probability that birds, particularly the English Sparrow, are the first depredators, the beetle only taking what is left.  I have observed black birds pecking the young ears of corn in the fall, leaving the milk oozing out of the kernels, and have no doubt that this would attract even innoxious insects.”

The BugLady’s beetles probably emerged as adults fairly recently and will be foraging through September.  They will overwinter as adults in the soil and resume their feeding (and breeding) in early spring (these beetles https://bugguide.net/node/view/727426/bgimage emerged in central Wisconsin at the end of March, in the bizarre, early spring of 2012).  Eggs are deposited near compost, soil, and manure piles, decaying wood, etc., and several sources said that Bumble flower beetles are among the species that will use ant nests.  Eric Eaton, in the Kaufman Field Guide to Insects of North America, says that their “Grubs have been found in the nests of ants,” so maybe it’s not a universal practice.  They pupate in a chamber they create underground.

Appearing to be a bumblebee helps keep predators away, and they’re pretty well camouflaged, and the beetles are also chemically defended, producing what is described as a “pungent chlorine-like odor.”

The BugLady was curious about the connection between the beetles and all the other insects feeding at the same trough.  Turns out that like the flower beetle, both species of butterflies come to fermenting fruit juices as readily as to flowers (and flies are, well, flies).  Whatever’s going on in those seed heads appeals to all.

Kate Redmond, The BugLady

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

Greetings, BugFans,

Sometimes, the origins of insects’ names are pretty inscrutable, but not that of the Seven-spotted Ladybug.  Its name does need a little unpacking, though – like the firefly/lightning bug, the ladybug/ladybird is a beetle (alternate name, lady beetle).  The Lady in question is the Virgin, to whom the people in the Middle Ages prayed when aphids were devouring their crops, and who is said to have responded by sending this species of aphid-loving beetle.  In gratitude, people named them “the beetle of Our Lady,” a name that proved cumbersome and was shortened first to “Our lady’s beetle” and then to “lady beetle.”  According to one source, its seven spots symbolize Mary’s seven joys and seven sorrows.

Perceptive BugFans are thinking, “Wait a minute – didn’t the Middle Ages happen in Europe?  Is this another exotic beetle species?  Yes and yes.  Its historic range is Eurasia (it’s said to be the most common ladybug in Europe), but it was introduced to North America in the 1950’s (and the 1960’s and the 1970’s) as a biological control.  Now, it can be found wherever there are aphids, which means ag-lands, grasslands, gardens, open woodlands, marshes, etc.

The Seven-spotted ladybug (Coccinella septempunctata), family Coccinellidae, is one of about 5,000 species of ladybugs in the world.  Most species come on a pretty basic chassis with a variety of dots and dashes against a background that varies from yellow to pink to red to black, sometimes within the same species.

At 7 to 10 mm long (¼” or so) the SsL is one of our larger ladybugs.  As promised, it has seven spots distributed over its elytra (hard wing covers).  The number of spots can be diagnostic in ladybug species, except when it’s not – Multicolored Asian lady beetles may have zero spots or many, and “teneral” forms, newly-emerged beetles whose colors haven’t “set” yet, can be deceiving https://bugguide.net/node/view/898160/bgimage.

Thorax patterns may be more reliable.  For instance, no matter what color they are or how many spots they have, most Asian ladybugs have a “W” at the top of the thorax (or “M,” depending on which side of the beetle you’re standing on).  The BugLady’s favorite pattern is the Red ladybug https://bugguide.net/node/view/1301740/bgimage, with its curlicues.  There are two, white spots on the SsL’s face, and its thorax is mostly black, with the head framed by two white “squares.”  The large, black spot at the front of the elytra is bordered by a white “bowtie.”

In North America, booming populations of SsLs may be out-competing native ladybugs (they are considered by some to be invasive); while in England, where they’ve sometimes occurred in disconcertingly large swarms, SsL numbers have declined with the influx of the Harlequin/Multicolored Asian ladybug.  For the story of the infamous Asian ladybug, see https://uwm.edu/field-station/multicolored-asian-ladybug-family-coccinellidae/.

SsL’s are promiscuous, mating several times a day.  Females may lay eggs on aphid-rich vegetation immediately, or, in fall, may store sperm and lay eggs in spring so their larvae have a more robust food supply.  Adults overwinter in a state of diapause (dormancy) in leaf litter, dense vegetation, under tree bark, and in other sheltered spots, often with other SsLs (up to 200 of them) that they attract using pheromones (and when spring comes, it’s party time).

A female can detect the “odors” of eggs of other ladybug species and will avoid placing eggs in the wake of another female.  When it hatches, a larva eats its egg shell and any unhatched eggs of its siblings, and then starts in on aphids and other small invertebrates that it finds on the leaf’s surface (including, alas, monarch eggs and tiny caterpillars).  When they are small, they simply suck out their prey’s juices, but older larvae chew up the whole thing (ladybug larvae are always likened to tiny alligators).  Ladybugs are unusual among insects with complete metamorphosis (egg-larva-pupa-adult) because both the larvae and the adults occupy the same spaces and eat the same thing (in a pinch, adults may eat pollen and nectar, too).

Several sources said that during its lifetime, a single SsL can put away as many as 5,000 aphids!  How do they find the aphids?  They pick up on the chemical traces emitted by plants that are being grazed by aphids, and they can also sense the alarm pheromones of the aphids themselves.

Ladybugs pupate right out there on the surface of the leaf; read about how they get away with it at https://uwm.edu/field-station/ladybugs-three/.

And speaking of “out in the open,” how does a brightly-colored beetle live in plain sight without getting eaten?  Like other ladybugs, SsLs release toxic/bad-tasting droplets from their leg joints when threatened (reflex bleeding).  So, their bright colors are aposematic (warning) coloration.  Despite that, they are eaten by other ladybugs and by a variety of spiders, birds, and small mammals, and they entertain many parasites.

For an informative, off-beat approach to ladybugs and some great pictures, see https://askentomologists.com/2018/03/12/ladybug-meme/.

FUN FACT ABOUT SSLS – they are the State Insect of five states.  The BugLady always thinks it’s a waste when State Insects are non-native (other categories, too – the State Birds of Delaware and Rhode Islands are chickens).  Wisconsin’s State Insect is the European honeybee https://en.wikipedia.org/wiki/List_of_U.S._state_insects.

Kate Redmond, The BugLady

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

Howdy, BugFans,   

The BugLady has trouble wrapping her head around the idea of a non-native butterfly, especially one that’s considered a pest.  What could be more benign than a butterfly?  But, there’s the non-native Cabbage White butterfly (there’s even an alien orchid that’s considered invasive in some areas – read https://northamericanorchidcenter.org/non-native-orchids/ for more about that).  Of course, when butterflies are listed as a pest species, it’s because of the dining habits of their caterpillars.

European Skippers (Thymelicus lineola) fetched up on these shores (London, Ontario, to be exact) in 1910 – one source speculated that the eggs were carried in the seed heads of the also-alien timothy grass, possibly in dried grass that was being used, pre-“plastic peanuts,” to cushion a shipment of ceramics (a common practice in by-gone days and one that brought other alien grasses from the Old Country).  The ES has been expanding its range ever since, both under its own power and as eggs transported in hay (in a study of hay bales, researchers found more than 5,000 ES eggs in a single bale of timothy hay, and another source referenced a range map for ESs and said that if it was more than two years old, it was out of date).

They are a “cool-climate” butterfly that ranges across Canada and the northern tier of states (largely skipping the Great Plains), and throughout the Northeast, and they’re found in all sorts of grasslands, plus parks, gardens, roadsides, and wetland edges.  They are common within that range, sometimes mind-bogglingly so.  According to the wisconsinbutterflies.org website (https://wisconsinbutterflies.org/butterfly), “This species is most impressive for its occasional abundance, far greater than that of other skippers in the northern states. The record high for this species on a single North American Butterfly Association count is 55,340 and every year the highest count is well into the thousands.”  Bugguide.net says that “It is becoming the most common skipper and considered a threat to Polites peckius” [Peck’s skipper].

European Skippers are in the Skipper family Hesperiidae and in the Grass skipper subfamily Hesperiinae.  Adult Grass skippers tend to perch on flowers with their wings slightly “ajar” – the forewings held closer together than the hind wings (which can make seeing the color patterns tricky) – and the host plants of their caterpillars are mostly grasses and sedges.  The caterpillars may web a few grass leaves together as a shelter and feed nocturnally.  On the other side of the Pond, European Skippers are called Essex Skippers.

They’re a smallish butterfly with a wingspread of 1 to 1 ½ inches and the typical chubby, hairy body of a skipper.  Like many grass skippers, they are orange and brown, but orange (one site describes it as “pumpkin orange”) predominates both on the upper and lower surfaces of the ES’s wings.

ES caterpillars eat timothy grass and, to a lesser extent, a few other exotic grasses.  Timothy, a sun-loving grass whose seed heads look like mini-cattails, came over on the boat from England, too, probably before 1700, as a contaminant in other plant materials.  The settlers here recognized it as a good livestock food and started cultivating it (England caught on later), and it continues to be important horse and cattle fodder today (it’s also sold as food for pet rabbits and rodents).  It’s named after a farmer named Timothy Hanson, who played Johnny Appleseed by spreading the grass from New England to the mid-Atlantic coast by 1747.  It’s sometimes planted as a soil holder in road construction.

The caterpillar damages timothy grass by its feeding, sometimes stripping the leaves of a plant, and when a lot of caterpillars are present, by eating the seed head, too, leaving a bare stalk.  According to a slightly-dated entry on the Canadian Biodiversity Information website, “Even after almost a century it seems that native parasites have not yet developed a ‘taste’ for this species” (although a naturally-occurring virus can be lethal to them and is being considered where caterpillar control is needed).  Adults nectar during the day on a variety of composites (fleabane, thistle), clovers and other mid-summer wildflowers.

Males patrol, close to the ground, searching for mates.  Females lay as many as 30 pale green eggs, in strands of three or four each, on grass leaves or seed heads.  Alone among all of the 275 species of North American skippers, ES’s overwinter as eggs, and the caterpillars emerge in spring.  Here’s a caterpillar, https://bugguide.net/node/view/294788/bgimage, and here’s a pupa https://bugguide.net/node/view/124322/bgimage.

Adults tend to sit out very hot or cloudy weather, and they spend the night perched down in the grass.

Speaking of orchids, the BugLady found an interesting paper about the effects that foraging ESs have on seed production in the spectacular Showy Lady’s-slipper orchid.  Orchids are famous for the tricks they play on potential pollinators and the hoops they put them through.  A number of orchids are pollinated by “naïve bumblebees” (a term that tickles the BugLady).  The orchids advertise their flowers by odor or color; the bees enter, and they find no nectar reward, but they leave bearing pollen.  It takes a few unrewarding visits before an individual figures it out and moves on to more rewarding flower species, but there are always more naïve bumblebees out there.

In the case of Showy lady’s slippers, pollinators are lured into the slipper and are trapped in it because the tissue around the lip’s opening is folded into the flower.  The only way out requires them to squeeze past hairy structures that first relieve them of any pollen they are carrying and then deposit new pollen on them before they reach the narrow exit – with no nectar for their efforts.

In one study, the majority of Showy lady’s slipper flowers in a study bog in Ontario contained one or more dead ESs, which can’t escape by the normal routes (one flower held seven!).  Males outnumbered females, because male ESs emerge from their chrysalis earlier than females.  Once an ES gets into the flower, pollination by the normal pollinators – leaf-cutter bees, syrphid flies, and a few small beetles – becomes difficult-to-impossible and seed production plummets.  If the ES can’t escape, like the naïve bumblebees, it can’t learn to bypass the orchid.

So – rising populations of ES have the potential to impact Showy Lady’s slipper populations https://www.researchgate.net/publication/318441873_European_Skipper_Butterfly_Thymelicus_lineola_Associated_with_Reduced_Seed_Development_of_Showy_Lady’s-slipper_Orchid_Cypripedium_reginae.

Kate Redmond, The BugLady 

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

Greetings, BugFans,

The BugLady is spending as much time as she can in the field (and the rest of it editing pictures) because, you know, the Summer Solstice has passed, and a little wave of warblers moved through her yard the other day, and winter is coming.  Many of these beauties have already starred in their own BOTW.  In a nutshell – there’s a whole lot of romance in the air.

CICADAS are calling https://uwm.edu/field-station/dogday-cicada-family-cicadidae/.  Historically, we’ve had lots of Dog-day cicadas in Southeastern Wisconsin (and very few of the famous Periodical cicadas), but there are other voices, too.  Along the Mississippi, some species sing well into the night.  The BugLady Googled “Cicadas Wisconsin” and found this nifty site: http://www.cicadamania.com/genera/usa.php?category=A&qs=WI

JAGGED AMBUSH BUGS (a common name shared by about 20 species in the genus Phymata) are pretty high on the BugLady’s list of favorites. They are fierce predators with a lot of attitude wrapped up in that little body.  When the BugLady sees an inert (and sometimes sizeable) insect dangling from a plant, the predator at the other end is inevitably a crab spider or an ambush bug.

When the BugLady is editing ambush bug pictures, she often discovers a well-camouflaged second ambush bug, or even a ménage a trois in a flower.  Bugguide.net tells us that “Coupling may involve several males riding around on a single female. Sometimes it allows them to take down larger prey, although coupling individuals have been found each with their own prey as well.”

ANTS CARING FOR TREEHOPPERS – Some species of ants (and wasps and bees and other insects) supplement their diet with honeydew, a sugary liquid that comes out of one end of an aphid or treehopper when it takes in plant sap (which comes out under pressure) through the other end.  Ants “farm” the honeydew producers, protecting them from predators, and in return they are allowed to “milk” their “livestock.” Win-win.  Animals (and plants) that have symbiotic relationships with ants are called myrmecophiles.

It’s BLISTER BEETLE season.  Black blister beetles (Epicauta pennsylvanica) conspicuously prowl the goldenrods in August.  These elegant gray and black beetles are members of the Epicauta cinerea group, which includes six, very similar species north of the Rio Grande that can be gray and black, or all gray, or all black.  The BugLady suspects that these are Clematis blister beetles (Epicauta cinerea), because they were crawling around on Virgin’s Bower vines.  The first stage/instar larva of many blister beetle species is a “larva on steroids” called a triungulin – a very mobile critter that actively searches for its food.  When it locates prey, it settles down as a normal, sedentary grub.  Members of this genus eat the eggs of many grasshopper species.  Look, but don’t touch: https://uwm.edu/field-station/blister-beetle/.

Some blister beetles have an elaborate courtship – as the BugLady watched this pair, the male advanced from the rear, rocking back and forth, twirling his antennae and maxillary palps (paired appendages below the mandibles, used for sensory and feeding purposes).

This TULE BLUET is carrying quite a load of water mite nymphs on its abdomen.  Like their tick relatives, the mites feed from the outside of the dragonfly.  They climb on board an almost-mature dragonfly or damselfly naiad while it is still under water, but they don’t feed.  When the adult pulls out of its old exoskeleton, they attach themselves anew while it is resting and its new exoskeleton is still soft.  A big mite load can sap the insect’s energy, shorten its life, and, depending on where they’re attached, even interfere with reproduction.  For a good article about mites, see: http://nwdragonflier.blogspot.com/2012/01/mite-y-dragons-odonata-and-water-mites.html

CRAB SPIDERS are masters of camouflage, with the ability to change their color from yellow to white, and back.  It takes up to three weeks to go from white to yellow, but only about a week to turn from yellow to white.  Why?  Because the yellow pigment has to be produced, but to go back to white, the pigment just has to be reabsorbed and excreted.

They don’t spin “trap webs” like the orb weavers, but they’re not above creating a little shelter, and this one webbed some ray flowers together for a bit of extra camouflage.  Pollinators beware!

PHANTOM CRANE FLIES are about as magical as it gets.  They are a subtle movement flickering at the corner of your eye on the dappled edges of wetlands – like those stars at night that you can only see by looking slightly to the side.  Slim, leggy flies, they fly/drift through vegetation, aided by ridges on their tibiae that catch the breeze like tiny sails https://uwm.edu/field-station/phantom-crane-fly/.

It’s hard to connect this LACEWING LARVA with the delicate, golden-eyed adult Green lacewing.  The BugLady started to write a brief bio about lacewings, and then she found this great video: https://www.youtube.com/watch?NR=1&v=fbRK6E5crbg&feature=endscreen.  Lacewing larvae like to drop out of trees onto the BugLady and bite her.  Wikipedia tells us that “the larvae may also occasionally bite humans, possibly out of either aggression or hunger.”  Definitely aggression.

GREAT BLACK WASPS are impressive wasps that dominate the flower tops in the second half of summer (there are a few species of blue-black mud wasps that look similar but are smaller).  If you look closely at her legs, you can see golden fringes near her feet.  Those are milkweed pollinia, sticky, saddlebag-shaped structures that are found within the flowers.  The BugLady sometimes finds lesser Hymenopterans, like honeybees, suspended from flowers when one foot gets stuck to a pollinium (she takes a grass stem and detaches them) https://uwm.edu/field-station/great-black-wasp/. 

WHITE-LINED SPHINX MOTHS have big population booms periodically – the last one was in 2013, and they were everywhere.  The BugLady was watching some hummingbirds squabbling over a patch of Bouncing Bet late one afternoon and she realized that one was smaller than the rest https://uwm.edu/field-station/white-lined-sphinx-moth/.  Yeah – a little out-of-focus – working on it.  Be on the lookout.

TREE CRICKETS are starting to sing https://uwm.edu/field-station/tree-crickets/, though this one is a bit too young to join the chorus.  Hear the full line-up at http://entomology.ifas.ufl.edu/walker/buzz/cricklist.htm.

Like other Odonates (damselflies and dragonflies) the male STREAM BLUET initiates this dance by transferring sperm from the tip of his abdomen to a receptacle neat its base.  When he grasps a female in back of her head (not a totally benign process – the BugLady has pictures of Spreadwing damselflies with bits of tissue stuck to their claspers/cerci), the female reaches forward and retrieves it, forming a “mating wheel.”  Later, he will guard her as she oviposits, to keep her from being stolen by a rival male.

And finally, what is summer all about, if not Technicolor, as illustrated by this VICEROY BUTTERFLY sitting on a prairie dock leaf?

GO outside – look at bugs (while ye may)!

Kate Redmond, The BugLady

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

Howdy, BugFans,

Meet another of the BugLady’s new neighbors, a handsome black beetle with red epaulets called the Red-shouldered Pine Borer.  It came to her front door – well, actually, it was trapped in her front door, between the screen and the raised glass of the storm door, and its rescue involved dismantling the glass/screen assembly with one hand while holding a jar beneath the beetle with the other (empty flip-top Parmesan cheese containers make excellent bug jars).  Five days later, it happened again, with the appearance of the red individual.

Red-shouldered Pine Borers are in the Long-horned beetle family Cerambycidae, so named because of their long antennae, antennae that make them favorites of entomologists (and collectors) everywhere.  Some have spectacular antennae indeed https://blogs.massaudubon.org/yourgreatoutdoors/have-you-seen-this-beetle/ (click to enlarge the picture of this extremely threatening beetle).  Cerambycidae (from the Greek kerambex – beetle – and keras – horn) is a large family with about 30,000 species worldwide and just under 1,000 in North America.

They are in the Flower longhorn subfamily Lepturinae, a group known for their, slim, sometimes-exaggerated wedge shapes and their habit of visiting flowers by day (they like “flat” flowers like Queen Anne’s lace rather than deep, tubular ones).  There is only one species in the genus Stictoleptura in the New World, and it’s divided into three subspecies distributed across a big chunk of North America except for the Southeast.  In his book Beetles of Eastern North America, Evans describes the range of our subspecies, Stictoleptura canadensis canadensis, as Newfoundland to Pennsylvania west to Ontario and Minnesota.

The elytra (hard wing covers) of RsPBs come in a variety of colors including all red, all black https://bugguide.net/node/view/371891/bgimage, and almost all black https://bugguide.net/node/view/998834/bgimage.  Bugguide.net tells us that the first individual that the BugLady found is unusual because its antennae were black, not banded; the second (red) beetle had a few pale bands on its antennae, but the bands can be pretty noticeable https://bugguide.net/node/view/26315/bgimage.

Another name for the Cerambycids is the Round-headed borers.  As you might guess from those long, breakable antennae, it’s the larvae that earn the “borer” label.  In general, Cerambycids may live from one to three years, mostly in the larval stage, and in general, the larvae don’t kill trees, they tunnel in and initiate the breakdown and recycling of stressed trees and dead and decaying wood (except for prairie species, which feed in plant roots).  Larvae of the RsPB are found in fir, pine, and hemlock.

Adult Cerambycids may eat sap, fruit, leaves, pollen, nectar, and fungi.  Any arthropod that crawls across flowers is, by default, a pollinator, but the RsPB is probably not an important one.  In reference to beetles’ contribution to pollination, the BugLady was tickled to learn the term “mess and soil pollinators.”  According to the US Forest Service, “Beetles were among the first insects to visit flowers and they remain essential pollinators today. They are especially important pollinators for ancient species such as magnolias and spicebush. Beetles will eat their way through petals and other floral parts. They even defecate within flowers, earning them the nickname “mess and soil” pollinators.”

(The beetles she found were on the inside, looking out, and the BugLady is hoping that’s because the door is porous, and not that the cedar walls of the cottage will soon be toast.)

Alas, the Wikipedia write-up of the RsPB is not a shining example of crowd-sourcing https://en.wikipedia.org/wiki/Stictoleptura_canadensis.  It’s a very brief and general account of the whole family Cerambycidae, not of the species; it reads like a bad translation, and it was subsequently cut and pasted unquestioned by a number of other legitimate internet sources like inaturalist.  Caveat emptor.

Kate Redmond, The BugLady

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

Salutations, BugFans,

This is National Moth Week – find a celebration near you.

July is turning out to be Beetle Month, and here’s a beauty.  It’s a Rove beetle, family Staphylinidae, a beetle family that rivals the weevils (and the Ichneumonid wasps) for the title of largest animal family (and scientists are still discovering new species).  It will lose its place if a proposal to divide the Staphylinidae into four families gains traction.

Anyway – the Rove beetle family is varied in size, color, diet, and habitat.  In general they are mostly drab beetles with truncated elytra that nevertheless shelter a pair of flying wings folded together like a tiny work of Origami.  Most are carnivores or scavengers, and most carry on their lives out of sight.  Over the past 200,000 millennia, various Rove beetle species have adapted to live on tidal beaches and wetland edges, and in moist microclimates under rocks and loose bark, in fungi, manure, caves, burrows, and leaf litter, as inquilines (borders) in the nests of ants and termites, and as pest controls (eating flea and fly larvae) in the nests of some tortoises, birds, and mammals.  And more.  Some are dramatically chemically defended (and some of the inquiline beetles deploy “appeasement” chemicals).

See http://entnemdept.ufl.edu/creatures/misc/beetles/rove_beetles.htm for a good general biography of Rove beetles.

Scenic Side Trip:  The University of Florida article mentions that among the places that rove beetles may cohabit are “communal nests of butterflies in Central America.” (Entomological) Social butterflies?  Yes – caterpillars of the Madrone/Mexican butterfly (Eucheira socialis) in the family Pieridae (Whites and Sulphurs) are gregarious.  And (a little lagniappe) according to the very readable and prolific Gilbert Waldbauer in Fireflies, Honey and Silk, “The silken walls of a tent, a communal nest, constructed by one hundred or more cooperating Mexican butterfly caterpillars (Eucheira socialis) have served as a unique writing surface in both prehistoric and historic times.  Eucheira is one of an extremely small number of gregarious nest-building butterflies, but there are many such gregarious species among the closely-related moths… ‘The Aztecs,’ notes Richard Peigler, ‘called [this] insect xiquipilchiuhpapalotla, which means butterfly that makes a pouch.’  He describes the walls of the tent as resembling parchment paper in texture and color and being so tightly woven and tough that they could only be cut with a sharp knife.  These silken sheets were used as writing paper in Mexico at the time of the Spanish conquest.”

We have visited rove beetles before in the form of the Hairy rove beetle, the rusty-tailed Platydracus and the amazing Shoreline rove beetle https://uwm.edu/field-station/shoreline-rove-beetle-family-staphylinidae/.

According to bugguide.net, there are at least 30 described species in the genus Ontholestes, only two of which live in North America, and only one of which is native.  The name comes from the Greek onthos(“dung”) and lestes (“robber” or “pirate”).  The Gold and Brown Rove Beetle (Ontholestes cingulatus) is native, and it can be found in the northwestern and eastern US and across Canada, often associated with fungi, decaying organic material, and dung piles, but it’s also found in grasslands and is considered an indicator of undisturbed forests.

At first glance, GaBRBs might be mistaken for fireflies because of the iridescent yellow hairs (setae) on the thorax and abdomen, but it’s not bioluminescent – it doesn’t have the equipment. The “glow” depends on the angle you view it from, and one author suggests that it warns predators about the beetle’s potential for chemical warfare.  Here’s a much better picture than the BugLady’s – https://bugguide.net/node/view/188718/bgimage, and the BugLady rarely sends BugFans to commercial photo sites, but these are beautiful pictures: http://www.cirrusimage.com/beetles_rove_o_cingulatus.htm.  In one of the BugLady’s pictures of the GaBRB, the wings are fully extended along the abdomen, and in the other, they are almost completely concealed.

The adult is about ¾” long, and the larva is about an inch – on the large side for Rove beetles – with impressive mandibles https://bugguide.net/node/view/199498/bgimage.  When alarmed, adults run around with the tip of their abdomen raised in a threatening fashion, like a scorpion.

After mating, GaBRB males guard females as they oviposit near fungi or carrion or other decomposing organic material.  Guarding takes the form of, at least, blocking a rival’s advance, but the encounter may escalate to frantic circling of the female by the two males and, at worst, to wrestling/biting.  Females are relatively scarce, and interloper males will take advantage of the fact that she may still be receptive, and the fact is, the majority of the offspring are likely to be sired by the most recent male.  The larvae feed on carrion or fungi, and the adults eat the inevitable flies, maggots, and larvae of other beetles that are found those habitats.  The larvae pupate in chambers in whatever substrate they’re in.

(it’s happened again – Spellcheck has informed the BugLady that her 113 page working document of partially-researched upcoming BOTWs has too many misspelled words and grammar errors, the result of much cutting and pasting and lots of scientific and author names.  Consequently, all spell-checking will cease until she fixes the whole document.  Apparently, it’s the boss of her.)

Kate Redmond, The BugLady

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

Greetings, BugFans,

Another week, another alien beetle eating an alien thistle.  The BugLady found this pair of weevils while she was chasing Thistle tortoise beetles (clearly, it’s a weevil that gets a lot of mileage out of its food plant).  And, in the “Ain’t the Internet Grand” category, a Google search for “weevil on thistle” resulted in a quick ID.

It’s a small weevil in the Snout/Bark beetle family Curculionidae.  To put things in perspective, with 400,000 species and counting, the beetle Order Coleoptera is the largest Order in Class Insecta (in fact, beetles are the largest Order of animals, period, accounting for a quarter of animal species).  Curculionidae (70,000 species) is the largest beetle family and one of the largest animal families.

It’s a small weevil with some big names – the Thistle Head Weevil and the Nodding Thistle Receptacle Beetle (NTRB) (Wikipedia defines “receptacle” as “the thickened part of a stem (pedicel) from which the flower organs grow”). Like the Thistle tortoise beetle, of very recent BOTW fame, the Nodding Thistle Receptacle Beetle (Rhinocyllus conicus) is not originally from these parts; it hails from Eurasia and North Africa.  It was introduced to control the alien and invasive Nodding/Musk/Russian thistle (Carduus nutans) and a few of its relatives, and now it’s at home in pastures and grasslands and road edges over much of North America.

 

NTRBs are about a quarter of an inch long and have a fairly short snout.  They are dark/black in color, but freshly-emerged individuals are mottled with a coat of short black and yellowish hairs that makes them look like they’re dusted with pollen.  The hairs wear off over time, leaving the beetle bald https://bugguide.net/node/view/1374096/bgimage. 

In early summer, beetles congregate, and boy meets girl.  Females lay between 100 and 200 eggs, two to five at a time, on the bracts of the developing thistle flower buds https://bugguide.net/node/view/487333/bgimage, and then top each egg with frass (bug poop) (alternatively, some sources say she caps the eggs with chewed-up plant material).  The cap dries and protects the eggs from predators, and one source said that the cap attracts ants, which care for the eggs.  Newly-hatched larvae dive into the flower head where, according to Wikipedia, they feed inside the receptacle on flower parts and developing seeds – one larva may consume as many as 25 seeds.  The plant reacts like a gall, growing tasty tissue around them, which the larvae also eat.  Despite their secretive lifestyle, the larvae are found by parasitoids.

As they feed, frass that collects inside the flower head is mixed with masticated plant material to form a stiff chamber that becomes the pupal case.  Flower heads contain multiple larvae, and the combined pupal chambers may form a large, hard mass.  After pupation, the newly-minted adult lingers in its protective case for a while before exiting the flower.  Adults may chew on the leaves a little, but the larvae do the most damage.  NTRBs overwinter as adults and emerge early in the following summer to lay eggs and then die.  They are strong, diurnal flyers, but they are reclusive when they’re not feeding.

Biological control can be a “Be careful what you wish for” scenerio, and we are getting better at it, but the BugLady worries that at the base of any bio-control decision, there’s a value judgement about acceptable collateral damages.  The main story about this weevil revolves around its use to control Russian thistle, Milk thistle (Silybum sp.) and some non-native members of the genus Cirsium.  After an introduction to Canada was deemed successful in 1968, NTRBs were released in Virginia, California, Montana and Nebraska in 1969.  On some sites, thistle populations decreased by 80% to 95% in just a few years, and over the next few decades, weevils were deployed in most of the Lower 48.  They traveled to New Zealand in 1973, to Argentina in 1980, and to Australia in 1989.

It was assumed that the weevil would stick to its non-native targets, but by the mid-‘90’s, it was obvious that the NTRBs weren’t limiting themselves to exotic thistles.  While they specialize on thistles in the genus Carduus, a lot depends on synchrony – lining up their reproductive schedule with the budding of the plants.  At the edges of Russian thistle’s range, and when Russian thistle has finished blooming, the weevil showed a willingness to move to native thistles – in fact, it has been found in 22 of our 60-ish species of native Cirsium, some of them already rare.

(Remember – native thistles support a large and complex community of animals, from cohabitants of the thistle bud, to Goldfinches and small mammals that use the fluff for nests, to butterflies and native bees that eat pollen and nectar from the flowers, to bee keepers who bottle thistle honey, to herbalists who harvest thistles for their medicinal value.)

Apparently, other continents don’t have susceptible native thistle species, so North America is the only place where the NTRB is behaving badly.  It is now listed as invasive itself in several states and is barred from interstate shipment.

In a paper called “Rhinocyllus conicus – Insights to Improve Predictability and Minimize Risk of Biological Control of Weeds“(1999) S. M. Louda discusses the history and reality of this “experiment” [the BugLady’s word] and makes recommendations about future introductions.  He says:

“Hindsight now demonstrates that, although the logic and reasoning were clear, the conclusion that Rhinocyllus was unlikely to have any major ecological effects was incorrect. The case suggests that more information was needed in order to make an accurate prediction.”

There is enough evidence to suggest that this biological control agent should not be moved into the region surrounding the Great Lakes [Too late – there were several local releases in Wisconsin in the early 1980’s, and the weevil was documented on a native a Cirsium about 20 years later, 80 miles from a release site].

Perhaps most damning: “So, the weevil was released into Canada in 1968, and into the USA in 1969, after exploration and initial testing in Europe. And, research on its biology and interactions was done once it was brought into North America” [emphasis, the BugLady].

A review of information on the release of Rhinocyllus conicus to control of Carduus spp. thistles in North America suggests at least 8 lessons for future biological control efforts. (See https://www.invasive.org/publications/xsymposium/proceed/02pg187.pdf).

In the words of the Germans/Dutch/Pennsylvania Dutch/Scandinavians (lots of people claim this saying), “We grow too soon old and too late smart” (or, in the words of Benjamin Franklin – “Life’s tragedy is that we get old too soon and wise too late.”).  Not a luxury we can afford, ecologically.

By the BugLady’s (admittedly quixotic) method of counting, this is (drumroll) Episode #500 in the series!  What a journey!  (Founding BugFans – you’re getting old!)

Kate Redmond, The BugLady

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