Tag: water lily

Bug o’the Week – Waterlily Borer Moth

Bug o’the Week
by Kate Redmond

Waterlily Borer Moth

Howdy, BugFans,

The BugLady has enjoyed her vacation and is ready to dive back into writing original BOTWS (until she gets another body part replaced).  Here’s a small moth, to celebrate National Moth Week.

BugFan Freda sent a shot of a small chunk of water lily leaf sitting on a large chunk of water lily leaf.  “What,” she asked, “is happening here?”  After some general Googling, the BugLady landed on a moth called the China mark moth https://www.gardenpondskauai.com/waterlily-pest-management/, which has a similar “leaf sandwich” modus operandi.  Various articles put its range all over the map (you should excuse the expression).  Then Freda found a picture of a moth that had been hanging around the lily pads – the BugLady is putting two and two together here, and hoping they don’t equal five.

A number of moths in the genus Elophila share the name “Waterlily borer” (family Crambidae).  It’s a small genus with some 50 species worldwide; nine in North America.  They have in common larvae that eat floating-leaved or submerged aquatic vegetation and that create cases from bits of leaf to live and pupate in.  The larvae don’t have gills, but breathe through their cuticles.  The BugLady thinks this is Elophila gyralis, which is found in and around wetlands throughout North America, east of the Great Plains.  

The moth was a male.  Waterlily borer moths are sexually dimorphic (“two forms”) – males come in lovely, intricate patterns https://bugguide.net/node/view/2446685/bgimage, but the larger (1 ¼” wingspan) females are almost monochromatic https://bugguide.net/node/view/2426188/bgimage, https://bugguide.net/node/view/2299063/bgimage.  They come in quite a range of colors

It’s not surprising that the life history of such a small critter has some gaps in it.  Says the “Moths of North Carolina” web page: “The elliptical eggs are laid in masses of about 25-35 in the water and immediately sink to the bottom. The larvae hatch in about 12 days and begin feeding on the lower epidermis of the leaves of the hosts, which are generally white water-lilies (Nymphaea sp.). The larvae first feed on the lower leaf surfaces of the lily pads and skeletonize the epidermal tissue. They later feed from a mobile shelter that is made by cutting a patch of leaf from the edge of the leaf, or rarely from the central part of the leaf. The feeding larvae slowly move over the course of 10-14 days to the petiole. They then bore into the top of the petiole and use the petiole tissue as food. After tunneling about 2-3 cm deep, they reverse direction and rest head up at the burrow entrance where they feed at night or on cloudy days on the leaf tissue. During this time the larvae may remain covered by the patch of leaf that it brought with it, but this is often detached by wave action. The last-instar lines the cavity in the petiole with silk and caps it with coarse silk to form a pupation chamber. The plant responds to injury of the petiole by making a gall-like swelling around the site of the excavation. The adult emerges after removing the silken cap.  Populations in Michigan are univoltine [one generation per year], with the half-grown larvae overwintering, then resuming growth with the spring warm-up.”

“The Vermont Center for Ecostudies” web page paints a somewhat different (but maybe not mutually exclusive) picture.  “The caterpillars of the water lily borer moth feed on leaves and tunnel into the stalks of the lily pads. The adults live for just six days, but in that short time a female can lay up to 900 eggs on the surface of the lily pads. The tiny green caterpillars hatch and begin to feed on the leaves. After three weeks they’ve grown from just a few millimeters to over an inch long, turning a deep red color. Amazingly, the caterpillars swim to land using a porpoise motion with the rear third of their body. Once on land, they build a silk-lined chamber in the soil and pupate.” 

Water lily leaves are subject to many kinds of deterioration throughout the summer due to tissue wear-and-tear and decay, and to gnawing insects.  This moth is generally not considered a pest, but if your backyard aquatic feature contained some decorative water lilies (botanists separate the words “water” and “lily,” but apparently entomologists don’t), the surfeit of holes  https://www.floridamuseum.ufl.edu/andrei-sourakov/activities/and-thanks-for-all-the-lilies/ (top picture) wouldn’t thrill you.

Water lilies feed and offer a buoyant platform to a world of aquatic insects and other invertebrates, including snails and the microscopic rotifers (wheel animals) we all remember fondly from high school biology.  The BugLady hopes to do a feature on them someday.  In the meantime, here’s what the folks in Vermont have to say about their unique physiology, “Water lilies are in a quandary. Their roots need oxygen, but the muck beneath the water is anaerobic. To solve this, they pump up to two liters of air from the surface down to the roots each day during the growing season using a special gas conducting tissue running down the length of stem called the aerenchyma. Air enters tiny openings on the leaf, called stomata. While land plants have them on all surfaces of the leaf, they are only found on the upper surface of water lily leaves. When the sun heats the young leaves it creates a pressure gradient that forces air down the aerenchyma. As leaves age they lose this ability to pressurize air. The roots return carbon dioxide to the surface through these older leaves.” 

Go outside – watch water lilies.

Kate Redmond, The BugLady

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

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 – 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/

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