Tag: wetland

Bug o’the Week – Wetlands Month II – Common Water lily Planthopper revised

Bug o’the Week
by Kate Redmond

Wetlands Month II Common Water lily Planthopper revised

Salutations BugFans,

Week 2 of National Wetlands Month features an upgrade of an episode that first appeared in March of 2014.

Water lilies are important plants in aquatic ecosystems.  At the very least, they provide a dry spot for insects (and frogs and others) to perch on – at most, they are hearth and home.  Various parts of the plants are eaten by organisms ranging from snails to moose, and the broad leaves modify/shade/cool the aquatic habitat below (the BugLady was tickled to see a few fish hiding under a lily leaf on a very hot day).

A water lily’s leaf and flower stay on the water’s surface instead of being dragged under by the weight of its long stem because the flexible, hollow stalk is divided into a series of air bladders that buoy it up.  

A few insect species are serious water lily specialists, living out their days on the plants.  Like Lilypad Forktail damselflies, rarely seen away from them, whose connection is so strong that as they sit on a leaf, the tip of their abdomen is bent down touch it.  And like Donacia beetles, whose eggs are laid at the base of the lily leaf and whose larvae attach themselves to the underwater parts of the plant, from which they get both food and oxygen, pupating in a silken cocoon that is dry inside because the air bubbles that leaked from the chewed stem and provided oxygen to the larva have blown the water from the cocoon. 

The rhizome of yellow water lily was an important medicine and food of Native Americans (they ate the seeds like popcorn, too), but white water lily was used more for medicine.  Henry David Thoreau (that silver-tongued romantic) associated the white water lily with young men picking its flowers on their way to church in Concord, and also said that the flower “reminds me of a young country maiden…wholesome as the odor of a cow.”  He reported smoking a stem once and said that it was the “most noxious thing I ever smoked.” 

The water lily community has many stories to tell, and the BugLady has already written a few of them.  Here’s a tale about some awesome little bugs that she met for the first time at Riveredge Nature Center toward the end of July, 2013 (at the time, BugFan Joanne said, “I’m in wetlands all the time, and I’ve never seen these before!”  Ditto!).  Some of the water lily leaves hosted masses of the planthoppers for a few weeks, but then they disappeared.  Despite searching for them every summer since then, it wasn’t until the summer of 2023 that the BugLady finally found another one (one!).  

COMMON WATER LILY/POND LILY PLANTHOPPERS (Megamelus davisi), known in more rarefied circles as the Davis’s Megamelus, are in the bug family Delphacidae, the Delphacid Planthoppers.  At first, the BugLady thought they were nymphs, because of their short wing pads, but they were adults.  Adult CWLPs come in either reduced-winged (brachypterous) or long-winged (macropterous) models https://bugguide.net/node/view/29578/bgimage, and the brachypterous form is more numerous. 

CWLPs are found in the eastern half of the US, but the species has made a surprise appearance in Hawaii.  They like ponds and extremely slow streams where white water lilies (genus Nymphaea) grow, and they are also found on the unrelated broad-leaved pondweed (Potamogeton natans).  Most of their relatives feed on grasses, but CWLPs eat any part of the water lilies or pondweeds that sticks up above the water line.  They’re considered pests if you’re trying to propagate young water lilies, but they don’t damage older, established plants.  Another species of Megamelus is welcomed as a biological control of water hyacinth in Florida. 

Their nymphs are meals for ravenous water treaders (Mesovelia sp. https://bugguide.net/node/view/1940717/bgimage); they’re attacked by a big-headed fly called Pipunculus varius, and their eggs are parasitized by an exceedingly tiny fairy wasp with the lovely name of Polynema ema https://bugguide.net/node/view/342131/bgimage, whose range exactly matches that of the CWLP because it has been introduced to Hawaii to hassle them there.  When a fairy wasp lays her egg on a planthopper egg, she “marks” it with her ovipositor so other females will leave it alone, because there isn’t enough food in the egg for two wasp larvae to share.  CWLPs are also noted in a website dedicated to “Fly Fishing Entomology,” although duplicating a fish food that is less than a quarter-inch long would take dedication, indeed.   

Females puncture water lily leaves, stems, and midribs to insert single eggs, and the plant obligingly produces tissue that covers the hole (the nymph’s eventual exit does leave a lasting scar, though).  There are three generations each year, and the fall generation, which outlasts the disintegrating water lily leaves, overwinters as almost mature nymphs in the leaf litter of shoreline plants.  When they become active again in late spring, they move out over the water and recolonize the lily leaves. 

So, what’s this little critter famous for? 

First, members of the family Delphacidae are outfitted with spurs (calcars) of various sizes and shapes on their hind tibias (“shins”), but CWLPs are overachievers – their spurs are described as “large,” “moveable,” and even “paddle-like” flaps complete with sensory hairs https://bugguide.net/node/view/1959085/bgimage.  There are any number of guesses about what these flaps do for the CWLP.  Are they oars that help CWLPs move across the water to new plants?  Are they skates?  According to a note in the 1923 “Bulletin of the State Geological and Natural History Survey of Connecticut,” “its large spurs undoubtedly support it when, by a mischance, it lands on the water.”  Or, queried the “Bulletin of the Buffalo Society of Natural Sciences” (Vol. 5, 1886–97), “Is not the large, foliaceous spur in this species an adaptation of Nature to enable these insects to leap more readily from the surface of the water, about which they make their home?”  [This theory seems to be the current front-runner.]   

Second, in the “When we try to pick out anything by itself, we find it hitched to everything else in the Universe” category, consider the planthopper-frog connection that has been documented in New York State.  Northern cricket frogs (Acris crepitans) love to eat CWLPs during the summer (they also like aquatic springtails).  CWLPs are the primary food of cricket frogs as the frogs prepare for their own fall migrations to wintering sites, too.  According to the (terrific) New York State Conservationist magazine, “a single cricket frog might spend several hours on one lily pad, devouring planthoppers as they move by the thousands over a lily pad.” 

In a paper called “Species decline in an outwardly healthy habitat,” forensic ecologist Jay Westerveld describes the crash of Northern cricket frog populations over much of New York State.  It seems that aerial spraying for Gypsy moths (now renamed Spongy moths) in the 1970’s wiped out entire populations of CWLPs.  When cricket frog numbers plummeted, investigators noted that they could find no CWLPs where they had once been plentiful.  Since spraying isn’t done over public water supply areas, pockets of cricket frogs remain in some wetlands adjacent to reservoirs.  Westervelt makes the point that the CWLP is a habitat specialist, and the Northern cricket frog is a food specialist.  Because the majority of CWLPs are wingless, natural recolonization by the species is painfully slow, and the bugs may need to be reintroduced in order for the frog to rebound. 

Forensic ecologist – the BugLady is ready for the TV series. 

And – PERIODICAL CICADAS – the gift that keeps on giving: https://www.smithsonianmag.com/smart-news/from-dinner-parties-to-restaurants-cicadas-are-landing-in-the-kitchen-180984321/?utm_source=smithsoniandaily&utm_medium=email&utm_campaign=editorial&spMailingID=49735720&spUserID=ODg4Mzc3MzY0MTUyS0&spJobID=2700967876&spReportId=MjcwMDk2Nzg3NgS2.   

Kate Redmond, The BugLady

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

Bug o’the Week – Closed for June I – Scuds, encore by Kate Redmond

Bug o’the Week
by Kate Redmond

Closed for June I Scuds, encore

Salutations, BugFans,

The BugLady usually closes for the month of June so that she can hit the trails, find newly-minted insects (preferably ones that she hasn’t written about yet), and start building up a stash of pictures for future episodes – by spring, her picture files are dominated by unidentified insects.  Also, having hit 700 episodes at the end of March, the BugLady feels the need for a victory lap/vacation.  Never fear – there will be something buggy in your mailbox every Tuesday in June.

We’ve spent the last five weeks celebrating American Wetlands Month, but really, every day is Wetlands Day, so here’s an encore episode from 2011 that was in the queue when we ran out of Tuesdays in May.  New words; new pictures.

SCUDS

Sit down and put your feet up, it’s a long story.

OK, the BugLady could (and will) regale you with all sorts of arcane facts about scuds (aka amphipods or sideswimmers), but the main “take-home” here is that scuds are a hoot!  And they’re pretty cute, too.  What impresses people about scuds is their locomotion – they zip around in your collecting basin, pausing under the shelter of vegetation, and then they’re off again.  In The New Field Book of Freshwater Life, Elsie B. Klots says that they walk and crawl, “skittering’ on their sides by flexing and extending their entire body, and frequently rolling up on their sides or back.”  Anne Haven Morgan, in her Field Book of Ponds and Streams, adds that “Amphipods are accomplished water acrobats and can climb, jump, swim or glide with equal ease.”  

Their pedigree: Scuds aren’t insect “bugs”, but they are located under the giant umbrella of the phylum Arthropoda, along with insects, crayfish, scorpions, spiders, sowbugs, centipedes, fairy shrimp, and more.  Arthropods (“jointed legs”) are a mighty bunch that includes more than three-quarters of all animal species!  Within the arthropods, scuds are in the subphylum Crustacea, class Malacostraca, and the order Amphipoda.  That’s a bunch of big names for a small critter, and it doesn’t stop there – common names for this often indistinguishable bunch include freshwater shrimp, scud, sideswimmer, and gammarid (Amphipoda includes a large family, Gammaridae).  The taxonomy of these critters is, of course, under review.

Most Amphipods are Marine, but there are about 150 species of freshwater scuds in North America.  They are secretive bottom-dwellers, gracing cool, well-oxygenated springs and pools that have some calcium in the water for their shells (one source linked the size of scuds to the availability of oxygen in the water).  They prefer waters that are “fish-lite,” and they may grace these waters in huge numbers, up to 10,000 per square meter.  Look for scuds in tangled vegetation or under decaying leaves.  Through these thickets, they crawl and pull themselves along, using clawed legs and bodily contortions.  

Some species of amphipods are highly specialized, living in hot springs, caves, marine estuaries, or in deep, underground springs, and others are able to survive the drying of ephemeral ponds by burrowing into the mud.  The presence of some kinds of amphipods testifies to a waterway’s purity, but many species of scuds are tolerant of varying degrees of pollution.  They can’t live in poorly-oxygenated waters, and some species have fairly limited temperature “windows.”

The BugLady read of behemoth scuds that grow as large as an inch, but most are barely half of that.  Like a flea, a scud’s body is ultra-streamlined – arched and laterally flattened (if you look at them head-on, they’re pretty slim).  The front end (cephalothorax) consists of the head and the first segment of the thorax and is home to eyes, antennae, and mouth.  That’s followed by seven segments of thorax, with each segment bearing a pair of long climbing/walking legs (the first two pairs end in claws that are used in feeding and mating).  Gills are located at the base of the thoracic legs.  The last six segments are the abdomen, with six pairs of shorter appendages/legs that aid in locomotion and also push oxygenated water toward the gills (Amphipoda means “both kinds of foot”).  Scuds come in a variety of mostly neutral to pastel colors (influenced by their diet) and are often translucent.  Telling one genus from another may require a microscope.

So, how does a scud make sense of the world?  Scuds are light-averse, preferring starlight to sunlight.  Their two pairs of antennae are sensitive to both touch and smell.  While many amphipods see through well-developed, functioning, compound eyes, species restricted to caves and underground springs may be eyeless or have only vestigial eyes (but well-developed tactile hairs).  Normally-eyed species may evolve into blindness when restricted to permanently dark environs.

And where do little scuds come from?  Males and females swim piggy-back for days, preparatory to The Act.  If she needs to molt during that period, they separate briefly and then get back together after she has shed.  Like water sowbugs, female scuds have a structure called a marsupium on the underside of their thorax.  He passes sperm to her, and it mixes with the eggs (1 to 50 of them) in her marsupium.  She will carry the eggs around for one to three weeks until they hatch, and then she’ll carry the little tykes for an additional week.  If the dissolved oxygen in the water decreases, she may “ventilate” her marsupium by moving her first three pairs of abdominal legs to create a current.  The next time she molts, her fully-developed (but microscopic) young are released.  

The young scuds shed their exoskeleton eight or nine times on their way to adulthood (the exoskeleton splits across the back between two thoracic segments; the front half of the body is pulled out of the old exoskeleton first, and then the rear half), and adults continue to shed throughout their lives (which, if they’re lucky, may span more than two years).

The BugLady encountered a bit of amphipod ambiguity about whether a female breeds more than once.  Pennak, in his venerable Fresh-Water Invertebrates of the United States, states that most species of amphipods breed only once.  Other sources say that females can have several broods (up to 10) between April and October, but they must dance the dance each time.  According to Morgan, a female that produces 22 eggs every 11 days potentially has 24,221 offspring in a year (but egg mortality is high).

What do they eat?  Scuds are listed as detritivores, which means that they eat detritus – fragments of decaying organic stuff (including their own, shed skins) – from the water around them.  This “recycling” – breaking down organic materials into ever-smaller pieces for re-use by ever-smaller critters – is an important ecosystem service.  They also graze on the thin layer of algae, fungi and bacteria that covers submerged leaves, and although only a few species are predators, scuds may nibble on dying or freshly-dead aquatic critters.  They use those first two pairs of clawed feet to hold a morsel while they chew on it.  Scuds tend to live in waters too constricted and shallow for fish, but fish can be a major predator.  In the Western lakes where scuds were introduced as trout food, they make up almost a half of the trout’s diet.

If you Google “freshwater amphipods,” most of your hits will be photos and scientific articles, but if you Google “freshwater scuds,” you’ll find fishing sites and opportunities to buy scud-like lures. Several of the fishermen’s sites point out that scuds are related to shrimp and propose that although they are small, scuds might taste good in garlic sauce (what wouldn’t??). The presence of the usual compliment of parasites in scuds suggests culinary caution.

About the humble scud, the Pond Informer website says, “Apart from being nutrient recyclers, they collectively serve as a high-quality type of food for secondary consumers. They aren’t just consumed by fish; they are also a favorable prey type for larger crustaceans, wetland birds, amphibians, semi-aquatic reptiles, and riparian mammals. Gammarids are often considered ‘keystone’ species wherever they occur because their presence helps shape and establish working patterns for the existing ecosystem.” 

When she posted this episode in 2011, the BugLady said that it wasn’t known how scuds got from one pond to another.  She received an email from BugFan Don, who wrote, “Back in the good old days when I still went duck hunting, we would get ducks like bluebills and ring necks that had lots of scuds on their feet and leg feathers.  They would still be alive when we got the ducks home. To suggest that these diving ducks carry scuds from pond to lake is not unreasonable.

Duck hunters called them shrimp. I’ve heard stories about seeing retrieving dogs covered with the things.  These tend to be stories of the past, though.  No one seems to see scuds in such abundance any more.

The minnow sellers in western Minnesota have introduced fathead minnows into a lot of the big shallow lakes that were used by the divers [diving ducks] that fed on the scuds.  Bluebills leave Minnesota in worse shape than when they entered.  It takes a really severe winter to kill the fatheads so they tend to persist and they decimate the scud populations.  The divers responded by moving their migration and resting sites further west, into South Dakota.  The minnow merchants prospered, in spite of laws that prohibit moving live fish from pond to pond.” 

John Muir was right – everything IS connected!

Fun Fact about Scuds – according to J. Reese Voshell, Jr. in A Guide to Common Freshwater Invertebrates of North America, “scud” comes from a Norwegian word, skudda, which means “to push.”  The word was Anglicized as scud “and came to mean to move or run swiftly.”

Another Fun Fact about Scuds – an American scud that somehow made its way to Europe is out-competing the native scuds and is considered invasive.

Every day is a Wetlands Day.

Kate Redmond, The BugLady

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

Bug o’the Week – Wetland Homage V – Water Strider by Kate Redmond

Bug o’the Week
by Kate Redmond

Wetland Homage V Water Strider

Howdy, BugFans,

Rounding out American Wetlands Month, the BugLady would like to give a shout-out to our hard-working, home-grown Wisconsin Wetlands Association.  The WWA reminds us that 75% of Wisconsin wetlands are on private lands, and that effective wetland protection involves educating both landowners and policy-makers.  To learn about wetlands in Wisconsin, check the Wisconsin Wetlands Association website https://www.wisconsinwetlands.org/ (and they wouldn’t turn down a donation, either).

WATER STRIDER REVISITED   (2012)

Anyone who has watched Water striders in action has been wowed by the four-point shadow that marks their path over shallow waters.  Photographers chase them, often futilely – a literal flick of the wrist sends the wily Water strider out of focus at speeds of one meter per second.  The BugLady first wrote about Water striders in February of 2008 and decided to take a second look.  What she discovered changed the episode’s rating from “G” to “PG.”

Water striders are in the True Bug Order Hemiptera, and in the family Gerridae.  There’s also a family of half-pint Water striders called the Riffle bugs/Broad-shouldered Water striders, (Veliidae), and in some cases, it takes a microscopic internal examination to distinguish one family from the other.  Sources disagree about how many species we are graced with – estimates range from 45 to 85 species of Gerrids in North America and from 750 to 1,400 worldwide.  Most are found on quiet or slow-moving fresh waters, but about 10 percent live on salt water. 

They have lots of common/regional names – water spiders (they’re insects, but if you count more than six legs, take a nose-count, too; it might be two Water striders in tandem – more about that later), pond skaters, water scooters, magic bugs, water skeeters, and in some parts of the South, “Jesus Bugs” (because they walk on water).  Many species are long and thin; some have wings and others are wingless, and some species have both winged and wingless forms, depending on where they live.  Most measure half an inch or less, but there’s an eight-inch Vietnamese water strider that’s billed as the largest invertebrate working the water’s surface. 

Each pair of legs has a different task.  The short, hooked, front pair catches food; the second pair rows the Water strider from one place to another; and the third pair, the longest, may do a bit of rowing, but it usually steers.

How do they DO that?  The top layer of water molecules (the surface film) is “stickier” than those below because of its contact with the open air.  Water striders skate on the water’s surface film on tiny, non-wet-able hairs at the bottoms of their tarsi (the final leg segments – their feet).  According to J. Reese Voshell, Jr. in A Guide to Common Freshwater Invertebrates of North America, retractable claws are located above the bottoms of their feet, so the claws do not puncture the surface film as they skate.  Long, thin legs allow them to distribute their weight over a larger surface.

Their legs and bodies, too, are covered by hydrofuge hairpiles (water-repellant hairs), at a density of several thousand hairs per square millimeter!  Raindrops and splashes of water roll off without weighing the Water strider down, and if by chance they are submerged, air trapped in the hairs helps them bob to the surface and gives them something to breathe during the trip.  Water striders can hop up off of the water’s surface, and many species can fly.  When they are working the surface film, they breathe like terrestrial insects, through openings in the sides of the body. 

The folks at MIT have, of course, dissected Water strider propulsion.  The feet of Water striders create tiny dimples on the water where they sit.  When they locomote, their feet push down and back, forming a small indentation off of which they rebound, moving forward as if bouncing on a trampoline (for every action, there is an equal and opposite reaction – life is physics) (while they were at it, the MIT researchers built a Robostrider using an aluminum soft-drink can.  Of course.). 

What are they doing on the surface film, anyway?  A lot of eating.  They have, like other true bugs, piercing-sucking mouthparts.  Their prey are small terrestrial invertebrates that fall, or mistakenly fly, down onto the surface film and get stuck in it, sending out tiny ripples that mark their throes.  Water striders monitor the surface film with their front legs and skate toward the disturbance.  They also feed on tiny animals that float up from below, like emerging gnats and midges and mosquitoes.  Pierce, slurp, discard, repeat.   

Birds prey on Water striders, and so do some other aquatic Hemipterans, but because of a nasty secretion from their scent glands, only the hungriest fish will eat them.  If Water strider populations get dense, they may solve the problem with cannibalism.  They are sometimes infested by the red nymphs of Water mites.

Water striders practice Simple/Incomplete metamorphosis – they hatch (from eggs laid on plants and stones under the water or near its edge) looking like mini-adults.  They shed and grow over a period of about six weeks before reaching maturity, adding a few all-important adult appendages, living in the same habitat as the adults, and eating the same food.  The adults of the summer’s final brood overwinter at the bottom of the pond, in plant stems, or out of the water, sheltered along the shoreline in winter.  

Males and females defend their own territories during breeding season but abandon territories and congregate cooperatively at other times of the year, even sharing a “kill.” 

The BugLady discovered, upon revisiting the Water striders, that they have pretty gritty sex lives.  Here’s the “G-rated” version.  Water striders, especially males, do a lot of signaling in the form of ripples as they move about; they have ripple signals to communicate “repel” (when they want to be alone), “threat,” and courtship.  A male in courting mode may send out a repel signal to a passing Water strider, and if the signal is not returned, he sends out a courtship signal.  If she is receptive (female Water striders are the deciders), he may stick with her during the whole breeding period. 

And here’s the PG version: According to articles in Discover magazine in 2010 and 2012, reluctant brides of some common Water strider species may be blackmailed by males who skate up and grab hold.  If she resists his charms (by deploying a genital shield), he starts tapping rapidly on the water surface.  Researchers think this might have started off as a simple demonstration of his fitness, but the behavior evolved into something more sinister.  Another predator of animals caught in the surface film is the Backswimmer, who hunts from below, and ripples created by the male Water strider are known to attract Backswimmers to the scene.  Scientists postulate that the female, especially if she has encountered Backswimmers before, is aware of the danger (she is, after all, the one whose belly is closest to the Backswimmer – the male is shielded by her body), and she yields to the male in short order, whereupon he stops tapping.  They noted that males are aware of the Backswimmer’s presence and actually tap faster when Backswimmers are around. 

After the mating process, the male may stay on her back for up to two days, which hampers her hunting prowess. 

Evolution is at work again in the strategy developed by a small genus of Water striders.  When the male is a nymph, his antennae are only somewhat thickened, but in his final molt, the antennae develop dramatic hooks and spines that match the shape of the female’s head and eyes and allow him to grasp her more firmly (even so, seven out of eight females manage to elude him). 

Magic bug indeed!

Kate Redmond, The BugLady

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

Bug o’the Week – Wetland Homage IV – Water Scorpions by Kate Redmond

Bug o’the Weeku
by Kate Redmond

Wetland Homage IV Water Scorpions

 Howdy, BugFans,

If wetlands are the transitional spongy/submerged/semi-submerged/sometimes-submerged areas between high ground and deep water, what might some wetlands look like?  Swamps are wet woodlands, while marshes are wet areas with standing water whose vegetation is mostly non-woody.  Peatlands like bogs, which have no sources of water other than precipitation and run-off, so water stalls there and becomes acidic; and fens, which are fed by springs and are often alkaline.  And then there are sedge or wet meadows, scrub/shrub thickets, and more (for more info, see https://dnr.wisconsin.gov/topic/Wetlands/types.html) and https://www.wisconsinwetlands.org/learn/about-wetlands/wetland-types/.

WATER SCORPION (2008)

The long (about 2” not including the “tail”), lean, well-camouflaged Brown Water scorpion (Ranatra fusca) is in the order Hemiptera, and thus, it can legally be called a “bug.”  It’s in the family Nepidae, which includes about 13 species in North America and 270 worldwide, including some broader-bodied species like https://bugguide.net/node/view/2205541/bgpage and https://bugguide.net/node/view/818188/bgpage that resemble the Water scorpion’s distant cousin, the Giant water bug https://bugguide.net/node/view/1657638/bgimage. 

Water scorpions have simple/incomplete metamorphosis, looking when they hatch pretty much like they will as adults, adding a few parts (the wings and the “naughty-bits”) as they molt (five times) and mature.  As is typical with insects that practice simple metamorphosis, both the adult and the immature water scorpions live in the same habitats – muddy-bottomed ponds and very slow streams with submerged vegetation – and both dine from the same menu.  What’s sauce for the goose is sauce for the gander.

They hang out, usually head-down https://bugguide.net/node/view/1682158/bgimage, on aquatic vegetation and in the detritus just off-shore, gripping with their second and third pairs of feet, legs bent.  Their passage through the water is sloth-like, and swimming, also using their second and third pairs of legs, is not their forte.  In fact, in A Guide to Common Freshwater Invertebrates of North America, author J. Reese Voshell, Jr. says that water scorpions are so sedentary that not only do algae and micro-invertebrates form colonies on them, but other aquatic insects may deposit eggs on them!  This immobility is part of their “stealth” hunting tactic.  

They’re equipped to fly https://bugguide.net/node/view/126649/bgimage, and fly they do, but not often, and almost always at night (say most – but not all – sources), and they must emerge and spread and dry their wings before take-off.  They are known to bask in the sun.

Despite their resemblance to the terrestrial, vegetarian walking sticks https://bugguide.net/node/view/1874213/bgpage, water scorpion are carnivorous, ambushing aquatic invertebrates like daphnia, seed shrimp (ostracods), backswimmers, water boatmen (a favorite), and even tiny fish fry and tadpoles.  They spot their prey with protruding compound eyes https://bugguide.net/node/view/1679712/bgimage, “lunge” at it by straightening their legs suddenly (without letting go), nab it with mantis-like front legs, stab it with a short beak (which is capable of piercing human skin, so handle with care), and inject it with tranquilizers and tenderizers.

Two long filaments on their south end are not stingers, but they explain the “scorpion” part of the name.  These lock together to form a breathing tube, the tip of which the bugs position just at the air-water interface.  Oxygen seeps down the tube and is stored as a bubble under the fore wings, against the abdomen.  They can use that bubble of air when they want to go deeper than their “snorkels” will reach (the structure of the filaments doesn’t allow water to enter), and in well-oxygenated water, oxygen suspended in the water can diffuse into the bubble, giving the insect extra breathing time. 

According to a website called the Pond Informer, “The mating process for water scorpions typically occurs in the months of April and May. To attract a female mate, a male will perform stridulation. He will create a chirping sound that is produced when he rubs his legs against his body, similar to crickets rubbing their wings together. Once he has attracted a mate, the male water scorpion will lay diagonally across and on top of a female, and he will grab onto her thorax using his front legs. Shortly after mating has occurred, the female will deposit her eggs – she usually does this around dusk.” 

Her eggs, which are laid at or above the water’s surface in plant stems, rotting wood, or in damp spots like algae and moss near the water’s edge, have respiratory filaments that protrude from the eggs and allow them to take in oxygen https://bugguide.net/node/view/1861200/bgimage, and some sources say that the eggs can also glean oxygen from the plant stems they are inserted into.  She can lay about 30 eggs in one evening.  Newly-hatched nymphs make a dash for the water’s surface (there’s no room for breathing tubes in the egg https://bugguide.net/node/view/570259/bgimage).  

Water scorpions overwinter as adults, under the ice, equipped with a chemical defense against freezing.

Fun Fact about Water scorpions – an alarmed individual may squeak, and then it may play dead, and it may squeak if it’s scooped out of the water.  

Another Fun Fact about Water scorpions – they can sense the depth of the water they’re in by the water pressure.

Kate Redmond, The BugLady

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

Bug o’the Week – Wetland Homage III – Water Fleas by Kate Redmond

Bug o’the Week
by Kate Redmond

Wetland Homage III Water Fleas

Howdy, BugFans,

We’re celebrating American Wetlands Month with up close and personal views into the lives of some of its citizens, as seen in some slightly refurbished, vintage BOTWs.

Wisconsin has about five million acres of wetlands these days, down from an estimated 10 million acres 150 years ago.  Early explorers referred to this territory as the Great Swamp, but today, only about 15% of the state is covered by wetlands.  Wetlands were considered waste areas that needed to be turned into something “more productive,” and they were drained and filled and altered, and many were used for dumps.

DAPHNIA(2012)

Back into the water we go and into the realm of another NETI – not the pot, the “Not-Exactly-True-Insects.”  Daphnia are at the lower limit of what the BugLady can accomplish with her 50mm macro lens (though she does have a recognizable shot of a Cyclops……), and Daphnia, aka water fleas, are yet another example of great stories coming in small packages. 

How small?  Pretty much at the edge of what the naked eye can easily detect/identify.  One source describes them as the size of the “equals” sign on the keyboard.  They’re listed as less than 5mm. 

The short version – daphnia are oval-ish, shape-shifting, widely-distributed, exhaustively-studied (right down to the pH of their teeny-tiny digestive tracts), unbelievably fecund, highly variable, planktonic, freshwater crustaceans.  That sentence bears a little “unpacking.” 

Who are they, scientifically speaking?  Daphnia are in the Phylum Arthropoda, subphylum Crustacea (like the water sow bug of recent BOTW fame), class Branchiopoda (with fairy shrimp and a few others), order Cladocera, and the family Daphniidae.  For our purposes one of the more common daphnia, Daphnia pulex, will serve as Everydaphnia.  According to Ann Haven Morgan, in her lovely Field Book of Ponds and Streams, “In 1669 the Dutch naturalist Jan Swammerdam described the common water flea as Pulex aquaticus arborescens – ‘the water flea with the branching arms’ – and ‘water flea’ it has remained ever since.”  It was officially described and welcomed into the Linnaean system in 1785.

You can see what?  A translucent carapace/shell of its own creation wraps around the daphnia’s thorax and abdomen.  The carapace looks like a tiny bivalve/clam-type shell, but it is actually a single, “folded” piece that doesn’t quite meet on the ventral (belly) side, forming two “valves” but with no hinge.  Neither the segments nor the first pair of antennae can be seen easily, and the legs are found in the gap between the edges.    

Based on an exhaustive study of daphnia anatomy, the BugLady figures that the dark ovals that can be seen on the dorsal side in some of her Daphnia pictures are young in the brood chamber.  The front blob on the adult’s head is the eye, and the second blob in the head seems to be part of the intestinal tract.  Unlike (almost all) insects, which do not molt after achieving maturity, daphnia molt about 25 times in their lives, and when they are in reproductive mode, they release a brood each time they molt.

How do they navigate their world?  Daphnia are found in all sorts of aquatic habitats, including ephemeral ponds but not including fast-moving or polluted waters.  Its large, compound eye rotates constantly, sensing changes in light intensity – daphnia don’t like light much, and many species move up and down in the water column from a pond’s surface to its floor several times during a 24 hour period.  The mouth, the small, first antennae, and the setae (hairs) on the ventral edge of the shell pick up “smells.”  These hairs on the ventral edge of the shell and the sensory hairs on the antennae are their touch “organs.”  They breathe through their body surface.  “Rowing” movements of the larger pair of antennae also provide the jerking locomotion that earned them the water flea moniker. 

Most individuals live only a short time, but some may live about a year, eating organic detritus, bacteria, algae, and some micro-zooplankton and dodging their many predators.  A current set up by their legs delivers food into the mouth.

Sex – or not: As soon as the water starts to warm, offspring are produced solo, by Mom (a talent called parthenogenesis).  She’s pretty good at it, too, popping out as many as 40 at a time, all female.  According to Morgan, “one Daphnia pulex produces a brood of eggs every two or three days [other sources said 10 days] and with its descendants it is said to produce 13,000,000,000 in 60 days.”  It only takes the young a few molts to achieve reproductive adulthood, and when they do, they already have eggs in their brood chamber.  Daphnia eggs hatch in the brood chamber, and the young stay there for a few days; they are released when Mom molts, at which time she reloads the brood chamber. 

While she is cranking out more and more offspring, the water temperature is changing (warming in summer or cooling in fall), the water is getting more crowded, food is declining, and the concentration of waste products is rising.  These stressors cause her to produce some male offspring (up to 50%), and orgies ensue.  The eggs produced by these sexual unions (which introduce some genetic variation) are called winter eggs.  Extra layers are added to the walls of the brood chamber for the winter eggs.  The whole “egg container” is called an ephippium, and the egg-filled ephippium is released as a unit that can survive winter cold and drought.  If the drought is temporary and the pool refills in fall, the eggs in the ephippium hatch (most of them are female) and the cycle is repeated. 

Shape-shifting?  The warming waters of summer may (or may not) cause individuals to change the shape of their head/helmet from rounded through pointy to absurdly pointy.  Predatory pressures may result in smaller, more transparent individuals that may grow neck spines (yes, the BugLady is a sucker for cool graphics – https://www.nd.edu/stories/little-giants/).  Here’s more https://northernwoodlands.org/outside_story/article/daphnias-changing-shape-stirs-a-debate.

Who cares??   Well, fish care – a lot.  Daphnia are bread and rice to many young fish, comprising up to 90% of their early diet!  Carnivorous bladderwort plants care, too; Morgan says that one bladder can hold up to three daphnia.  Aquatic insects also appreciate them, and wading birds.  Aquarists (not Aquarius’s) care – daphnia provide food for aquarium animals.

Scientists care.  The translucency of their carapace allows scientists to watch a daphnia’s innards at work.  Daphnia are almost universally available, are easy to rear in the lab/school, and look cute under (and can survive under) the cover slip of a slide.  You can subject them to alcohol, nicotine, prescription drugs, etc. and watch their reactions, study immunity, disease, cellular function, and more. 

Scientists are so enthralled with daphnia that they have worked out the genomic sequence (which wades deeper into scientific waters than the BugLady is comfortable going).  Suffice it to say that humans have 20,000 to 25,000 genes and daphnia have 31,907, more than one-third of which are unique to daphnia, and many of which are duplicates!  One of the legacies of the late, great entomologist Dr. Tom Eisner is the mantra that knowing the natural history of an organism can help us hypothesize what is/isn’t/should be happening internally.  Daphnia are short-lived critters that survive in constantly-changing conditions, and scientists think that the environment may help determine which of the duplicate genes will be expressed. 

The rest of us care, too.  In his Freshwater Invertebrates of the United States, Pennak says that “the water fleas have been favorite objects of observation by both amateur and professional biologists ever since the invention of the microscope.”  The BugLady was charmed to discover that there are daphnia tee-shirts.

And we can barely see them! 

Life is Physics. The various creatures of the surface film have developed different ways to navigate the meniscus—Water treaders actually “run” at the meniscus slope and then use their front legs to pull themselves “uphill.” The BugLady recommends this beautifully-photographed article about bugs and https://thales.mit.edu/bush/index.php/2005/04/14/wetting-climbers/ (you don’t have to do the math–the folks at MIT already did it for you).

Bugs in culture: “I was stunned by the perfection of the insects.”—Pablo Neruda

Kate Redmond, The BugLady

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

Bug o’the Week – Wetland Homage II – Water Treader by Kate Redmond

Bug o’the Week
by Kate Redmond

Wetland Homage II Water Treader

Greetings, BugFans,

The celebration of American Wetlands Month continues.

We’ve all seen the list of wetland benefits – wetlands recharge groundwater, protect us from floods by trapping water and releasing it slowly, improve water quality by absorbing pollutants and sediments (they’ve been called “the kidneys of a watershed”), protect shorelines from erosion, and provide recreation and beauty.  And they’re amazingly productive, biologically – they provide homes and habitats for many plants and animals (for 75% of Wisconsin wildlife species, says the Wisconsin Wetlands Association), and according to the Defenders of Wildlife organization, “More than one-third of our country’s threatened and endangered species live exclusively in wetlands, and almost half of these imperiled species use wetlands at some point in their lives.”  They are considered as productive as coral reefs and rainforests, and they feed us and multitudes of other animal species (“biological supermarkets,” said one report).

Without further ado — WATER TREADERS (2014)

As the BugLady was leaning over a pier photographing aquatic stuff last summer, she saw a mugging.  Turns out that she misidentified both the muggers and the mug-ee (and, probably, the motivation).  She thought that she was seeing a pair of young water strider thugs attacking a guiltless Mirid plant bug.  The two “water striders” rushed across a water lily leaf and grabbed the larger “plant bug” and scuffled with it, actually rolling it onto its back.  As the BugLady snapped pictures, the “plant bug” managed to get away and exited across the leaf to the left, while the delinquents ran away to the right. 

Fast forward eight months, when the BugLady was researching the Water lily planthopper (of recent BOTW fame).  One reference noted that “Water lily planthoppers are preyed on by Water treaders.”  Water treaders?  When the BugLady looked them up, she recognized them as the young hoodlum bugs (Water treaders are not to be confused with the larger, more delicate Marsh treaders—a whole different animal).  The third bug was also a Water treader.

And, when the BugLady looked at the pictures again, very carefully, she realized that what she initially interpreted as a mugging might instead have been two Water treaders sharing an intimate moment and being relentlessly interrupted by a third.

Mulsant’s Water treader (Mesovelia mulsanti), named after a 19th century French entomologist-ornithologist, is fairly common in eastern North America and points south but is easily overlooked and has a history of being ID’d as the nymph of something else (which, of course, the BugLady did, too).  In the introduction to his 1917 publication “The Life-History of Mesovelia mulsanti,” H. B. Hungerford says that it “seems worthwhile to present some notes concerning the biology of Mesovelia mulsanti whose habits and life-history are certainly among the most interesting of all the bugs that walk upon the surface of the inland waters.” He proceeds, cheerfully, to do just that. 

“It is at home in the haunts of the marsh-treader on the floating vegetation growing in the shallow waters of the pools, where the clumps of sedge spread their slender stems upon the water from the bordering bank, where young cattails spring up and green algae carpet the surface of the waters.” (more Hungerford).

Mesovelia are about 5 millimeters small (1/4” max), with long antennae, long legs, and a long face.  Nymphs and most adults are silvery-green.  Like the water lily planthoppers that they dine on, adult Mesovelia come in uncommon winged forms – dark, with a white chevron on their backs (https://bugguide.net/node/view/1683522/bgpage) – or more-common wingless forms (there’s an “in-between” morph, too).  Their long legs allow them to scoot along pretty fast on the water’s surface and on vegetation, and to take little hops.

They have a simple/incomplete metamorphosis—a newly-hatched individual (a nymph) resembles an adult.  Food-wise, what’s good for the adult is fine for the nymph, and they sport sharp, piercing mouthparts.  Contemporary authors describe a fairly languid/passive hunting style, saying that WTs feed by scavenging dead or injured insects or insects that are stuck on the surface film (and that they may practice cannibalism).  Earlier researchers like Hungerford tell us that “Water Treaders eat insects and other small invertebrates; their hunting method is to run along the surface of algae and duckweed, and even along the surface of the water, until they have run down their prey.”

It’s not surprising to see them on a water lily leaf with aphids, and in the picture of the damselflies, the BugLady presumes that the female Skimming Bluet damselfly (the caboose of the tandem pair) was nipped in half by a hungry bird, and when the male landed on the water lily, the Water treader was attracted by the female’s hemolymph (bug blood). 

They also reach down through the surface of floating mats of algae and other plants and snag tiny crustaceans and aquatic insects that feed and shelter there.  When they catch something, they insert their “beak,” inject saliva/enzymes, and suck out their prey’s innards.

Hungerford again: “They are cautious creatures but do, on occasion, fall upon fairly lively prey. The tiny nymphs feed upon more gentle organisms in the water as there are few upon the surface that they are able to overcome. When offered springtails as suggested by Butler, disaster often followed…the hungry little creatures would attack them, only to be turned topsy-turvy upon the water even by comparatively small springtails.”

Mesovelia are eaten by fish and dragonflies, and nymphal water mites may parasitize them.

Ms. Mesovelia uses a specially designed ovipositor to pierce the stems of aquatic plants and ream out a hole.  She may lay as many as 100 eggs, each requiring a separate incision (“As frequently as not the male accompanies the female during the process. Having mounted her in mating he merely moves forward and remains perched upon her back as she busies herself with egg laying, mating being attempted and often consummated between her labors.” Hungerford).

The plants that she inserts her eggs into sink to the pond floor in winter and according to some accounts, the eggs hatch in spring.  There are probably several generations through the summer, but sources disagree about whether the final bugs of the year overwinter as eggs or as adults, hidden in the shoreline debris, bolstered by an internal antifreeze that keeps lethal ice crystals from forming in their cells.

Water treader vocabulary word—one of the two species of North American Mesovelia that have found their way to Hawaii is troglophilic.

Where do Mesovelia fit into the great scheme of things?  Within the order Hemiptera, in the infraorder Gerromorpha (infraorder is one of those potential notches between order and family that’s used as needed).  The Gerromorpha include water measurers, water striders, smaller/riffle/broad-shouldered water striders, and a few others.  As a group, they are sometimes called “semiaquatic bugs” or “shore-inhabiting bugs,” and one author calls them all “pond skaters.”  They are often seen locomoting across the surface of the water (including salt water— bugguide.net calls them the only true marine insects).  Water treaders are in the family Mesoveliidae.

How do they do it?  A “hydrophobic” (waterproof) cuticle and hairs are standard equipment on the Gerromorpha, and their long, water repellant legs allow the pond skaters, whose weight is therefore spread out, to push down on the water’s surface without punching through.  Check the indentations on the surface made by a water strider https://bugguide.net/node/view/1751576/bgimage (curiously, the claws of a water strider are located up on its legs in order to avoid slicing the surface film, but a Water treader’s claws are in the normal spot at the ends of its tarsi). 

Another Water treader vocabulary word is meniscus (the curve of the upper surface of a liquid, caused by surface tension).  There’s hardly a concept more important to aquatic invertebrates than surface tension.  Because it is in contact with the air, that top layer of water molecules is “stickier” than those under it, and a certain force is needed to break through it, whether from above or below.  The “meniscus effect” results in tiny, slippery hills where the water’s surface curves up to meet the “edge” of the shoreline, and of plant stems, leaves, floating debris, etc.

Life is Physics. The various creatures of the surface film have developed different ways to navigate the meniscus—Water treaders actually “run” at the meniscus slope and then use their front legs to pull themselves “uphill.” The BugLady recommends this beautifully-photographed article about bugs and https://thales.mit.edu/bush/index.php/2005/04/14/wetting-climbers/ (you don’t have to do the math–the folks at MIT already did it for you).

Bugs in culture: “I was stunned by the perfection of the insects.”—Pablo Neruda

Kate Redmond, The BugLady

(Sharp-eyed BugFans who are wondering about the tiny, elongated, shapes in one of the pictures – good spotting – those are Cyclops https://uwm.edu/field-station/cyclops/)  

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

Bug o’the Week – Wetland Homage I – Water Sow Bug by Kate Redmond

Bug o’the Week
by Kate Redmond

Wetland Homage I Water Sow Bug

Howdy, BugFans,

May is American Wetlands Month.  So, all month, BOTW will celebrate by posting slightly-massaged (a few new words and pictures), encore episodes about a selection of awesome critters the BugLady has encountered in area wetlands, plus some wetland information.

To start with – what exactly is a wetland?  There are some pretty technical definitions out there that include wetland soil types and lengths of time that soils are submerged, but the US Geological Survey’s definition is more intuitive.  Wetlands are transitional zones between well-drained upland areas and deep water systems.  The water table in wetlands may be at or just below the surface of the land, or the soil may be covered by shallow water.  Some wetlands are permanently wet; some are periodically dry; some are wet at high tide.  The BugLady is reminded of a video she once saw of Canadian Naturalist John Acorn, wearing boots and standing in a squishy area, saying “Wet!  Land!  Wet!  Land!” as he lifted and put down one foot and then the other.

WATER SOW BUG

This story about Water Sow bugs was first posted in 2009.

Another foray into the world of the “almost-insects.” Like insects, Water Sow Bugs are in the Phylum Arthropoda (“jointed appendages”), and like their terrestrial cousins the sow/pill/potato bugs of previous BOTW fame, they are in the very diverse subphylum Crustacea (with lobsters and crabs and barnacles and more) and in the mostly-aquatic Order Isopoda (equal foot), a reference to their abdominal appendages.  They’re in the family Asellidae, the Common Waterslaters.  The BugLady couldn’t find any explanation for “waterslater,” and when she looked up “slaters,” it was defined either as 1) “someone who lays slate” or 2) as a water sow bug.  Maybe a reference to the overlapping segments of the exoskeleton?  The water sow bugs she photographed might be in the genus Caecidota.  

About the common name—they were named sow bugs because someone thought that the way the female cares for her young was reminiscent of sows caring for piglets.  Other names for these critters are water louse, aquatic sowbug, water hoglouse, and cress bug.

They are flattened for crawling under stuff, drab in color, and about ½” long.  They have three body segments—a cephalothorax (combined head and first segment of the thorax), a thorax (the next 7 segments) and an abdomen (everything south of that).  Jointed appendages?  They’ve got plenty.  Water sow bugs have 7 pairs of legs, one per segment of the thorax.  The first pair is adapted for holding; the rest of these boots are made for walking.  To that, add 6 pairs of short appendages on the underside of the abdomen, the final pair of which looks like two tails.  They breathe using gills located on the underside of the abdomen, and there are two pairs of antennae – one long and one short. 

Look for Water sow bugs in shallow water under dead leaves and debris – the more hiding places there are, the more Water sow bugs there will be.  One source calls them “secretive.”  They are designed to survive in low-oxygen and they prefer the lighting to be low, too.  Diet-wise, they are omnivore/scavenger/shredders that eat little pieces of detritus from the pond floor, bits of dead or injured animals, and live and decaying plants.  In turn, fish and many other aquatic animals eat them.

On the underside of each of the segments of the thorax, at the base of each leg, is a short, inward projection; these combine to form a shallow chamber below the thorax.  Female Water sow bugs use this thoracic chamber as a brood chamber or marsupium https://bugguide.net/node/view/1799296.  She carries her eggs there, and later, for a little over a month until they can fend for themselves, her young.  During that time, she fans the “plates” that form the marsupium so that the eggs/young are properly oxygenated.  That maternal solicitation is negated by the fact that she will sometimes eat her own offspring, and that the siblings may cannibalize each other.  

Wood frogs owe a lot to Water sow bugs.  Water sow bugs help to turn big pieces of dead plants and animals into little ones in ephemeral ponds. In the process, dead material is removed from the pond, and smaller chunks of material can be colonized by fungi and algae more easily.  These nutritionally-enhanced morsels of food are eaten by wood frog tadpoles and other herbivores. 

Fun Fact about Water sow bugs: though they live underwater, they are poor swimmers, getting from Point A to Point B by crawling.  Slowly. 

Another Fun Fact about Water sow bugs:  Old Wives say that if you have an upset stomach, you should eat a sowbug.  Turns out that (like Tums) their exoskeletons are largely calcium carbonate.

And if the worst that can be said of any of us, after we pass, is that we maybe cared a little too much for watercress, then we will have lived pretty blameless lives, indeed.

Kate Redmond, The BugLady

(Sharp-eyed BugFans who are wondering about the tiny, elongated, shapes in one of the pictures – good spotting – those are Cyclops https://uwm.edu/field-station/cyclops/)  

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

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