Silverfish and Firebrat

Among the more unusual insects to be found in the average home or workplace are the Firebrat and various kinds of silverfish, order Zygentoma, family Lepismatidae. They barely resemble insects, and are so primitive in their supposed evolutionary origin as to qualify minimally as part of the class Insecta.

Four-lined Silverfish, Kansas

Siverfish and firebrats were formerly classified in the order Thysanura, along with jumping bristletails, but due to the confusing nature of Thysanura (at one time it even included springtails), the order name reverted back to Zygentoma, as originally established by Börner in 1904.

Members of the order, and the family Lepismatidae, are easily recognized by their flattened, torpedo-shaped bodies, with long antennae, and three long filaments issuing from the tip of the abdomen. The long appendages often break, however, and specimens without the hallmark "tails" often confound the homeowner who finds one. The bodies of these insects are covered in short hairs and scales, which make them as slippery as a fish when a predator, or person, attempts to grab one.

There are nine genera (plural of "genus") with about fourteen species, in the family Lepismatidae in North America north of Mexico. Some domestic species are cosmopolitan in distribution, having been carried to the far corners of the globe in international commerce.

Among our common species are the Silverfish, Lepisma saccharina, Four-lined Silverfish, Ctenolepisma lineata, and the Firebrat, Thermobia domestica. Collectively, they range from 8-15 millimeters in body length. The rear-end (caudal) filaments and long antennae make them appear even larger.

Firebrat from Arizona

The Firebrat tends to prefer warm, dry situations, such as around furnaces and the insulation around water pipes; silverfish enjoy more humid surroundings.

Lepismatids are typically nocturnal, hiding in nooks and crannies by day. They can run nearly as rapidly as a cockroach when startled. They feed on all manner of carbohydrates, with a particular fondness for starchy materials. Among their favorite meals is the paste used in bookbinding. Consequently, they can be an occasional pest in libraries, warehouses, and storage facilities, especially those without climate control. Got wallpaper? Maybe not for long, as the paste adhering it to your interior is fair game. They also eat starch in clothing, particularly when on silk and rayon fabrics. Oatmeal, damp wheat flour, and cereals are also on the menu.

Silverfish and the Firebrat live a surprisingly long time: at least two years under laboratory conditions. They go through incomplete metamorphosis, the young stages resembling the adults but not being sexually mature. They molt a number of times to reach adulthood, but then they keep molting the rest of their lives. At least one specimen in the lab molted over forty times in a 2.5 year lifespan. Perhaps the molting replenishes the scales lost in the course of squeezing into crevices or slipping through a predator's jaws.

Because of their ancient lineage, lepismatids do not mate with internal fertilization. Instead, a male lays down a packet of sperm called a spermatophore when near a female. He then binds her loosely with strands of silk spun from glands in his mouthparts. Thus restrained, she has little choice but to pick up the spermatophore and insert it into her genital opening. I know, it sounds like a sequel to Fifty Shades of Grey. She eventually lays eggs singly or in small batches in cracks and crevices.

Four-lined Silverfish, Massachusetts

Thankfully, silverfish and the Firebrat are rarely abundant enough to be more than a novelty or a nuisance in the average dwelling, office, or other building. Should you feel compelled to control them, there are plenty of ".edu" websites that offer cultural, non-chemical, and chemical solutions. You might simply prefer to let predators like the house centipede do that job, though. What? That freaks you out even more?

Sources: Berenbaum, May R. 1989. Ninety-nine Gnats, Nits, and Nibblers. Urbana: University of Illinois Press. 263 pp.
Von Frisch, Karl. 1964. Ten Little Housemates. New York: The MacMillan Company. 146 pp.

Springtails

Imagine animated flecks of salt and pepper running, even jumping, all over the bathtub, shower stall, wash basin, or window sill. Maybe you don't have to imagine, maybe you have actually experienced this and thought you were seeing things. Welcome to the world of springtails, tiny invertebrates that are among the most plentiful of organisms, both indoors and out.

Classification

So primitive, in the evolutionary sense, are springtails that scientists cannot even agree whether they are insects. They used to be, as members of the order Collembola. These days they are more likely to literally be placed in a class by themselves: the class Collembola; and treated as "non-insect hexapods." Regardless, there is no denying their importance as members of the soil fauna, and instrumental in the recycling of nutrients there.

Size and Abundance

Springtails are very small. Most are 1-3 millimeters. A "giant" sprigtail may measure 6 millimeters. The largest known species reaches a maximum of 17 millimeters. What they lack in size they more than make up for in sheer numbers. Estimates of the number of springtails per cubic decimeter of (forest) soil vary from 200 to 1,800, probably according to soil texture, composition, and fertility. A decimeter, by the way, is one-tenth of a meter (Bellinger, et al., 2014).

Many springtails active at night on a porch

Habitat

The Collembola are not always restricted to soil and leaf litter. Some species inhabit caves, others inside rodent burrows, still others occupying intertidal zones. Some species live in ant or termite nests, still others on the surface of still waters, even the surface of the snow, hence the common name of "snow fleas" for Hypogastrura nivicola and its relatives. You probably have springtails in the potting soil of your houseplants, and around the drains of sinks, tubs, and basins. The one overriding prerequisite for the presence of springtails is the presence of moisture.

Food

Springtails feed on all manner of organic matter, but the majority seem to eat rotting plants, insect frass (poop), fungal hyphae and/or spores, pollen grains, or dead invertebrates. A few are predatory on soil micro-organisms like rotifers and tardigrades ("water bears"), while fewer still are predatory on other springtails and tiny insects. They cannot be considered pests, but could, in rare instances, be indicative of mold or fungal issues when found indoors.

Look closely: Many springtails from under a board in a field

Anatomy

Not all springtails....spring. Still, they get their common name from two peculiar appendages that most springtails possess. A forked, tail-like appendage called the furcula on the ventral (underside) of the abdomen projects forward from near the tip of the abdomen on its fourth or fifth segment. When "cocked," the fercula (aka furca or furculum) hooks into a latch-like organ called the tentaculum (or "retinaculum"), located on the third abdominal segment. When the tentaculum releases, the furcula is driven downward against the substrate (surface on which the animal is resting), catapulting the springtail up and away, often several times the creature's body length. This bouncing locomotion is certainly observable by the naked eye.

All springtails feature a "ventral tube" or collophore, on the underside of the first abdominal segment. It's function is poorly understood, but it has been suggested that it may act as an extra leg, helping the creature navigate slick surfaces by means of adhesion; it may also function as a grooming organ, and/or as an intake for liquid water.

Lastly, springtails can be identified by having the tibia and tarsus fused into a "tibio-tarsus;" by the simple eyes composed of up to eight ocelli; four- to six-segmented antennae; and mouthparts concealed by folds in the cuticle of the animal's face.

A large and ornate springtail from beside a stream

Life Cycle

The sex life of springtails is not terribly intimate. Males produce packets called spermatophores that contain sperm. He may make a direct deposit to the female's genital opening, but most species deposit spermatophores one at a time on the surface of the substrate. Sometimes the spermatophore is on a hair-like stalk. There are apparently a variety of strategies for improving the odds that a female will find and pick up the species-appropriate spermatophore in a timely fashion. Males will actively consume old spermatophores, so time is of the essence.

A mated female will lay eggs individually or in small clusters in the soil. The babies that hatch resemble miniature versions of the adults, and thus go through "simple" or "incomplete" metamorphosis, molting several times after emerging from the egg.

Interestingly, the adults continue molting, up to fifty times during their mature lifespan. This may be due to the fact that springtails absorb oxygen directly through their soft exoskeleton. Chinks in the armor may not facilitate proper metabolic processes.

Controlling indoor springtails

At worst, springtails should be considered a cosmetic nuisance, and certainly not worthy of chemical assaults. They are not considered a risk to human health, the health of pets, or destructive to property. If you must, here are some steps you can take to literally dry them to death, the only sure-fire "cure."

• Do not overwater houseplants. Should you find springtails in houseplants, take the plants outside and allow the soil to dry out for several days.
• Consider using a dehumidifier in the room where you are seeing springtail activity. Lowering the atmospheric moisture level is always helpful in minimizing or eliminating springtail populations.
• Spread a very thin layer of diatomaceous earth (DE) where you are seeing springtails, such as on a window sill. Reconsider this if you have curious pets or toddlers, as DE is essentially pulverized glass. Diatomaceous earth etches the cuticle of insects, causing them to dehydrate and die.
• Repair worn weatherstripping on doors, and seal cracks and crevices that springtails (and other arthropods) could crawl through to get indoors.
• Inspect firewood, toys, and any other objects brought indoors from outside. This is essential for preventing all potential pests from entering the home.

Sources: Bellinger, P.E., Christiansen, K.A., and Janssens, F. 1996-2014. Checklist of the Collembola of the World.
Berenbaum, May R. 1989. Ninety-nine Gnats, Nits, and Nibblers. Urbana: University of Illinois Press. 263 pp.
Hopkin, Steve. 2014. Collembola Photo Gallery.
Hopkin, Stephen. "The Biology of the Collembola (Springtails): The Most Abundant Insects in the World," The Natural History Museum (UK).

Little Bugs with a Big Bite: Minute Pirate Bugs

Sometimes it seems the tiniest of insects is the biggest nuisance. Mosquitoes come to mind, as well as black flies, and "no-see-ums" or "punkies" (biting midges in the family Ceratopogonidae). One other insect often responsible for surprisingly painful bites is the aptly-named "minute pirate bug." There are about 90 species in the family Anthocoridae found in North America, in 22 genera, but only a few cause us grief.

Insidious Flower Bug biting me in Colorado

The Insidious Flower Bug, Orius insidiosus is, appropriately, the species most likely to get under your skin. Well, on your arm, hand, or neck, where it will likely probe you painfully. At only 2-2.5 millimeters, it is possible to overlook it entirely when trying to pinpoint the source of your irritation. In the right light, however, the little bug appears bright white and black.

Despite dispensing unprovoked bites, Orius insidiosus is actually a highly beneficial bug. It is a predator of many crop pests like very young caterpillars of the corn earworm, plus insect eggs, aphids, whiteflies, thrips, and mites. Consequently, this minute pirate bug is reared commercially and sold to farmers as a biocontrol agent.

It takes only twenty days, on average, for O. insidiosus to go from egg to adult. Females lay two eggs per day, and about thirty during their lifetime. Each ovum is deposited in foliage such that the top of the capsule protrudes above the leaf surface. In about four or five days, the first instar nymph emerges from the egg. During the next two or three weeks, the nymph goes through a total of four more instars before transforming into a fully-winged adult bug. The adults live an additional three or four weeks.

Insidious Flower Bug biting me in Kansas

Adult Insidious Flower Bugs overwinter in leaf litter and probably other debris on the ground. Several generations can be produced annually over the insect's wide geographic range. It occurs east of the Rocky Mountains, plus parts of California, and has been introduced to British Columbia. Because it is available commercially, it has likely spread elsewhere, too.

Adult Anthocoris musculus, Colorado

Another species I have found commonly here in Colorado Springs is Anthocoris musculus. It is a real giant by pirate bug standards, measuring 3.4-4.0 millimeters as an adult. I have found it associated with cottonwood trees, and it is well-known from willows and other deciduous trees and shrubs as well as herbaceous plants.

Nymph of Anthocoris musculus, Colorado

It is potentially an important predator in orchards, and has been observed eating red mites and "eye spotted bud moth" in Nova Scotia (Kelton, 1978). This species ranges throughout most of North America including Alaska and northern Canada.

The next time the pirate bug bites, simply utter "Ar-r-r-r!" and remember their beneficial qualities. After all, they are probably keeping your garden free of other tiny pests.

Adult A. musculus feeding on unknown object, Colorado

Sources: "Minute Pirate Bug aka. Orious insidiosus," Evergreen Growers Supply.
Gibb, Tim. 2006. "Have a thick skin when it comes to Insidious Flower Bugs," Purdue Plant & Pest Diagnostic Laboratory, Purdue University Extension
Hull, L.A. and R.L. Horsburgh. "Minute Pirate Bug, Orius insidiosus (Say)," Mid-Atlantic Orchard Monitoring Guide.
Kelton, Leonard K. 1978. The Anthocoridae of Canada and Alaska. Ottawa: Canada Department of Agriculture. Publication 1639. 106 pp. (PDF).
Slater, J.A. and R.M. Baranowski. 1978. How to Know the True Bugs. Dubuque, Iowa: Wm. C. Brown Company Publishers. 256 pp.

Hackberry Psyllids: A Fixture of Fall

Sometimes, it is easier to identify an insect by the evidence it creates than by seeing the bug itself. Such is the case with the abundant, but tiny, hackberry psyllids, genus Pachypsylla in the family Psyllidae and true bug order Hemiptera. Psyllids are also known as "jumping plant lice" for their resemblance to aphids and ability to vault themselves away from danger.

Along one of the streets that borders our townhouse complex in Colorado Springs are a pair of hackberry trees, among the few planted ornamentals that are not oak, maple, or elm. They are invariably exploited every summer by Pachypsylla celtidismama, which produces "nipple galls" on the underside of hackberry leaves. The small, tumor-like growths do not seem to affect the health of the tree in the least, but provide housing and food for the tiny insect within each one. Up to 52 galls have been found on a single leaf (Caldwell, 1938), and they vary from smooth in texture to rather hairy. Double and triple galls are not unheard of, but it is rare to find more than one nymph occupying each gall.

The adult stage of hackberry psyllids will start appearing shortly, if they are not emerging already. Adults of P. celtidismama are only 3.5-4.5 millimeters in length from "nose" to the tips of the folded wings. They resemble tiny cicadas, but can also be confused with barklice, order Psocodea. Barklice have chewing mouthparts, though, while psyllids in general have beak-like piercing-sucking mouthparts they use to tap plant sap.

Hackberry psyllids make themselves a real nuisance when they start seeking nooks and crannies in which to hibernate. They can gather by the dozens, if not hundreds, on the exterior of doors, window screens, and the siding of homes. They pose no threat, of course, and simply hosing down the masses with water will solve the problem. The appearance of these insects en masse is a brief affair anyway.

A different Pachypsylla species

Next spring, female psyllids will deposit eggs on the leaves of hackberries at the precise time when the leaves begin unfolding from the bud. Should a psyllid deposit her eggs too early, or too late, and the chances of successful development of her offspring plunges dramatically.

The formation of the bulging gall is the tree's response to the feeding of the nymph that hatches from the egg. The little dome-like pocket insulates the nymph from hostile abiotic environmental factors, and protects it from at least some predators and parasites. The nymph goes through five stages, the last instar illustrated in the images below. Note the two pairs of developing wing pads. The spike-like projections on the rear of the insect will help it to cut an exit in the gall before it emerges as an adult.

Nymph of P. celtidismama © Hannah Nendick-Mason via Bugguide.net

Nymph of P. celtidismama © Hannah Nendick-Mason via Bugguide.net

Despite their seemingly impenetrable fortress, the nymphs are still vulnerable to tiny parasitic wasps, including Psyllaephagus spp. (family Encyrtidae), and Torymus spp. (family Torymidae). The larval wasps feed as parasites on the nymphs and then chew their way out of the gall once they complete development.

Psyllaephagus sp. © John Rosenfeld via Bugguide.net

This, and the other six species of hackberry psyllids, range pretty much wherever hackberry occurs naturally, and increasingly where it is used as an ornamental tree. The different species of psyllids make correspondingly different styles of galls, so it is easiest to assess the gall shape, size, and location to determine which psyllid is responsible. Keep in mind that gall midges (family Cecidomyiidae) can also create galls on hackberry.

You might try rearing a few galls to see what parasites emerge along with the adult psyllids. It is entirely possible you could record a new host record in the process.

Sources: Berenbaum, May R. 1989. Ninety-nine Gnats, Nits, and Nibblers. Urbana: University of Illinois Press. 263 pp.
Caldwell, John S. 1938. "The Jumping Plant-lice of Ohio," Ohio Biological Survey Bulletin 34, vol. VI, No. 5: 229-281.
Winterringer, Glen S. 1961. "Some Plant Galls of Illilnois," Story of Illinois Series No. 12. Urbana: Illinois State Museum. 51 pp.

Larder Beetle

Thanksgiving is an American holiday where we share a big meal with family and friends. Chances are, you might be sharing the leftovers with the Larder Beetle, Dermestes lardarius, as well.

Larder Beetles are members of the family Dermestidae, collectively known as skin beetles and carpet beetles. They feed as larvae and adults on all manner of dried animal products, the larger species enjoying cured meats, dry pet food, furs, taxidermy mounts, even cheeses. Their alias of “Bacon Beetle” gives a clue as to their food preferences. They can also be attracted to the carcasses of dead rodents between walls; or even accumulations of dead insects in light fixtures. I found this Larder Beetle larva crawling out from under our dog’s food bowl earlier this month, probably looking for a place to pupate.

Larvae of Dermestes lardarius average about 12-13 millimeters in length just prior to pupation. They are covered in long hairs like most dermestid larvae, but are distinguished by the pair of hook-like spines on the rear end.

Under optimal conditions, the life cycle from egg to adult can be completed in 40-50 days, but more commonly there is one generation per year. Eggs hatch in an average of less than twelve days after being laid in clutches of 6-8 by the female beetle in a food source. Larvae that eventually become adult male beetles undergo five molts, while female beetles pass through six molts in the larval stage. The insects may spend anywhere from 35-80 days as larvae, probably depending on how easy it is to secure enough food to complete the transition to adulthood. Larvae may wander in search of new food sources, too.

The pupa is enclosed in the last shed larval exoskeleton (“skin”). The larva bores into soft, but relatively solid material such as cork before pupating. The adult insect emerges in about fifteen days.

Adult Larder Beetles are 7-9 millimeters long, and blackish with a broad yellowish band across the elytra (wing covers) as shown. They can fly well. Note the relatively short, clubbed antennae that help distinguish them from other household insects and many other beetles. Adults can be long-lived, sometimes persisting for a year-and-a-half under ideal conditions. The species overwinters in the adult stage, too.

Prior to the age of refrigeration, the Larder Beetle and its cousins were serious competitors for stored food. Today, they are more of a nuisance pest. Prevention is the best way to control them. Store your vulnerable foodstuffs (including dry pet food) in durable plastic, glass, or metal containers with tight-fitting lids. Store furs, wool blankets and garments, and other fibers of animal origin in a cedar chest. Cedar has proven repellent qualities and is quite effective. Forget mothballs (utterly useless) and moth crystals (at least potentially carcinogenic).

I personally find these to be handsome beetles; and I admire their adaptability to exploit our own weaknesses in protecting resources we think are rightfully ours. In this season of giving, sometimes we give by accident. Happy holidays, everyone.

Sources: Bennett, Stuart M. 2003. “Dermestes lardarius (Bacon or Larder Beetle),” Stored Product Insects.
IPM.WG. 2012. ”Larder Beetle,” Museum Pests. Integrated Pest Management Working Group.
Klass, Carolyn. 2011. “Larder Beetle,” Horticulture Diagnostic Laboratory. Cornell University, Cooperative Extension of Suffolk County.

Red-shouldered Bug

Today’s edition of “True Bug Tuesday” is all about the Red-shouldered Bug, Jadera haematoloma, family Rhopalidae. Last week, my wife and I happened upon a large number of this species in various life stages here in Colorado Springs. I went back a couple of times to get more and better images.

At first glance, it is easy to mistake Red-shouldered Bugs with boxelder bugs in the genus Boisea. Indeed, they both fall under the more general category of “soapberry bugs,” named for the affinity of these insects for the fruits of certain trees in the family Sapindaceae. Their appetite extends far beyond the berries and seeds of those and other trees and plants, though. They have been observed feeding on flower buds, oozing sap, and even dead insects.

Adults of Jadera haematoloma are overall slate gray with fewer red markings than boxelder bugs. They measure 9.5-13.5 millimeters in body length. Some specimens are brachypterous, meaning they have shorter wings than normal, revealing a bright red abdomen with a black bar or two on those exposed segments.

Nymphs lack wings, so the front half is gray while the back half is red. The nymphs can get very bloated while feeding, as demonstrated by the one imaged below. The nymphs pass through five instars (an instar is the interval between molts) before reaching adulthood. Freshly-molted adults are bright pink or orange.

There are usually at least two generations per year, more in the southernmost states. The bugs mate “tail-to-tail” and are thus easily distinguished from solitary individuals. Females unreceptive to mating signal that fact to approaching males by making noise. They stridulate by rapidly rubbing lateral edges of the abdomen against the adjoining thoracic segments.

A mated female digs a hole about one centimeter in depth in dry soil. There, guarded by the male, she lays a batch of up to twenty eggs. The ova hatch in about two weeks. One female, which usually mates multiple times with different males, can produce between 400 and 800 eggs in her adult lifetime.

Both nymphs and adults can overwinter in cracks, crevices, and other cozy niches. They occasionally take shelter inside homes and other buildings like boxelder bugs, rendering them a “nuisance pest” in some places.

The Red-shouldered bug is also known as the Goldenrain Tree Bug. It is native to the U.S. from Virginia south to Florida and west to Wisconsin, Kansas, Colorado, Arizona, and southern California. South of the border the species occurs from Mexico and the Caribbean to Colombia and Venezuela. It has also been accidentally exported overseas, at least to Asia.

This insect is easily confused with boxelder bugs, and any number of seed bugs in the family Lygaeidae which can be of similar size, coloration, and abundance. One must look at various subtle structural characters, rather than color and pattern, to distinguish them with any degree of certainty. With practice, however, one can render a confident ID in the field.

Sources: Carroll, Scott P. 2013. “Jadera haematoloma,” Soapberry Bugs of the World.”
Eaton, Eric R. and Kenn Kaufman. 2007. Kaufman Field Guide to Insects of North America. Boston: Houghton Mifflin Company. 392 pp.
Jing-Fu Tsai, et al. 2013. “The soapberry bug, Jadera haematoloma (Insecta, Hemiptera, Rhopalidae): First Asian record, with a review of bionomics,” Zookeys 297: 1-41.
Slater, J.A. and R.M. Baranowski. 1978. How to Know the True Bugs. Dubuque, Iowa: Wm. C. Brown Company Publishers. 256 pp.

True Bug Tuesday: Brown Marmorated Stink Bug

Ok, ok, I confess. I watch that awful Animal Planet show Infested! What is often more appalling than the crises faced by the people showcased in the program are the rampant errors and hyperbole provided by many of the “experts.” One recent episode, however, was probably not overly exaggerated. It featured a family whose rural Pennsylvania home was overrun with Brown Marmorated Stink Bugs, Hyalomorpha halys, that were seeking winter shelter.

I have written about this invasive species previously, in a feature on ”Common Indoor Insects of Autumn”, having never seen one in person. That changed last year when my wife and I visited Cape May, New Jersey. Many structures, from buildings to Port-O-Lets, were being investigated by the bugs as potential winter hang-outs. The insects were also common on foliage and vehicles.

Since my first article, things have gotten even worse. H. halys is now found in most states east of the Mississippi River, plus the Pacific Coast states, and now Utah. Furthermore, it has elevated its status to that of a bonafide agricultural pest. In fact, it is essentially number one on the U.S. Department of Agriculture’s “most wanted” list.

The Brown Marmorated Stink Bug is what is called a “generalist” feeder, meaning that there are a wide variety of plants on its menu. Most insects are “host-specific,” unable to eat plants outside of one genus or family. The Monarch butterfly is a good example of a host-specific insect. The caterpillars can only eat the foliage of milkweed and closely-related plants. Contrast this picky diet with that of H. halys. Over 300 species of plants are palatable to it in the nymph and adult stages.

This versatility in host plants translates to a potent economic impact. The bug accounted for $37 million in losses to apple-growers alone in 2010. Other crops adversely affected include raspberries and blackberries; and organic farmers reported losses of beans, peppers, and tomatoes. The cosmetic damage alone can render some produce unsalable.

Like all true bugs, stink bugs feed on plant sap and juices through beak-like piercing-sucking mouthparts. Their sipping and sucking can cave-in corn kernels, wither fruits, and leave unsightly stains behind.

Adult male Brown Marmorated Stink Bugs also emit an “aggregation pheromone,” a kind of aromatic chemical cocktail that attracts other males, females, and nymphs to food sources. So, as if a single bug isn’t bad enough, he recruits friends and family. Scientists may be getting closer to using that pheromone as a weapon against the bug, by drawing them into traps, for example.

Back to that episode of Infested!. It had a happy ending. Initially demoralized by the overwhelming number of bugs holding them prisoner indoors and eventually infiltrating their home, the family turned the problem into profit. The father devised a light trap to attract and kill the bugs, and is now selling his invention to others.

Sources: Gibson, Caitlin. 2013. “Stink bugs could mount a comeback this spring,” The Washington Post, January 5, 2013.
Murray, Todd, et. Al. 2012. Pest Watch: Brown Marmorated Stink Bug. Washington State University Extension Fact Sheet FS079E. 5 pp..

Beast Into Beauty: Aphidlions

Perhaps no insects embody “beauty and the beast” better than the green lacewings of the family Chrysopidae. The average person would be hard-pressed to make the connection between the hideous larva and the delicate adult it is destined to become. Who could blame them? Gardeners might easily mistake the sickle-jawed immature stage as a villain rather than a hero.

The family name Chrysopidae translates to “gold eye,” and indeed the adults of some species of green lacewings have eyes that seem to have fallen out of a kaleidoscope. The family belongs to the insect order Neuroptera or “nerve-winged insects.” This name comes from the dendritic pattern of wing venation and is not to imply that the wings of these insects feel any kind of sensation, at least any more so than in any other insect.

There are fourteen genera and at least 85 species of green lacewings occurring in North America. No doubt more species await description by scientists. These are very abundant animals, and just about everyone, from city center to rural countryside, has had an adult green lacewing or two (or several) visit their porch light at night. What can easily escape attention, however, are the other stages in the life cycle of chrysopids.

Let’s start with the egg stage. Believe it or not, the little white balls on the ends of these hairlike stalks are lacewing eggs. One could mistake the egg clusters for the fruiting bodies of some kind of fungus, and when they appear on a leaf or stem, cause a gardener some degree of concern. The female lays her eggs on these stalks for good reason: to keep them out of reach of predators like….well, her offspring’s siblings for example. So voracious are larval lacewings that they will not hesitate to cannibalize a brother or sister right off the bat.

Larval lacewings are undeniably ugly: worm-like bodies studded in clusters of spines, with a head dominated by jaws that look like ice block tongs. As if they are aware of their own ugliness, the larvae of some species conceal themselves under a layer of debris that they stick on those clusters of spines along their backs. What goes into this “garbage pile” might include bits of lichen, dust, or even the bodies of their victims. The real reason the larvae disguise themselves is not to redeem their ugly appearance, of course, but to make them appear innocuous to their prey and hide them from their own predators.

Lacewing larvae prey mostly on aphids, which has earned them the nickname “aphidlions.” They won’t pass up the opportunity to kill a caterpillar or other insect, either. They simply approach a prey insect and grab it with their jaws. Puncturing the body of their prey, they inject fast-acting paralytic compounds and digestive enzymes that go to work immediately on the victim, essentially liquefying its internal organs and tissues. The aphidlion then draws out a fluid meal, also through its hollow jaws.

Aphidlions are themselves vulnerable to various predators, namely the ants that guard colonies of aphids. Aphids secrete a sweet, liquid waste product called honeydew, and this is highly coveted by ants. The ants therefore vigorously defend the aphids from their predators and parasites. So, those lacewing larvae hidden under a blanket of debris might more easily escape detection by ants than a naked aphidlion would.

Once it emerges from the egg, an aphidlion proceeds through only three instars (intervals between molts). A mature larva will then spin an opaque, silken cocoon before transforming into the pupal stage. The mature adult will chew its way out of the cocoon, leaving the empty vessel looking like a tin can with the lid hanging by a hinge of remaining metal.

The adult insect is delicate-looking but durable, and highly colorful. They find mates by a kind of Morse Code, drumming their abdomens in a species-specific rhythmic pattern that the opposite gender recognizes. So precise is this courtship “song” that some species can be separated only by differences in their tune. The species themselves are physically identical. The adults do feed. Some continue their predaceous lifestyle, but others feed on aphid honeydew, or nectar or pollen.

Green lacewings are best appreciated as living creatures. The color of their bodies and eyes quickly fades after death. Be on the lookout for the larvae, but be careful. There have been reports of bites from larvae that fall out of trees and onto people, with reactions to bites varying from a nuisance to extremely painful with relatively persistent effects. Mostly, lacewing larvae should be considered among your best friends when it comes to waging war on garden and crop pests.

Wasp Wednesday: European Paper Wasp

The Fourth of July holiday here in the United States celebrates our successful declaration of independence from British rule. Who would have thought that a bunch of settlers could pull that off? Well, the tradition continues as other European species continue to establish themselves on American soil. One of the most successful has been Polistes dominula, known here as the European paper wasp.

Note that this species has also been known as Polistes dominulus, but that name was a violation of Latin “gender” rules according to the International Commission on Zoological Nomenclature. No, there really is such an organization. I don’t fully understand the change, either, but I acknowledge that the Kaufman Field Guide to Insects of North America is in error. My bad, to be corrected whenever we are directed to turn out a revised edition.

The first observation of P. dominula in North America was made by G. C. Eickwort near Boston, Massachusetts in 1978. It is native to Eurasia, occurring over most of central and southern Europe, east to China and south to northern Africa and the Middle East. It therefore has a long history of living alongside people, and that affiliation is reflected in the largely urban distribution of the species here in the states. My own experience while collecting in Cincinnati was shocking. The European Paper Wasp went from an uncommon novelty in 1994 to probably the dominant species of Polistes by 1998. Now this species is known from most states and southern Canada, except for much of the Great Plains and Prairie Provinces (and apparently the Appalachian region as well).

Paper wasps are social, forming relatively small colonies. They build exposed combs from woody fibers they chew into a durable papery material. While the European Paper Wasp seems to prefer to nest in cavities (making them an enemy to those who put out bird boxes and check them), the species will also nest under the eaves of buildings and even among the tangled branches of shrubs. Nests peak at only a few dozen individual wasps, usually in late autumn.

Polistes dominula is rather small for a paper wasp, with a forewing length measuring 9-13 mm. Its compact body, relatively short legs, and bold black and yellow color pattern has contributed to it being mistaken for one of the yellowjackets, a different kind of social wasp in the same family, Vespidae. The orange antennae of P. dominula help one to identify the species with ease. No other social wasp in North America has orange antennae.

Like other paper wasps, the European Paper Wasp feeds its larval offspring pulverized caterpillars. The adult “worker” wasps are very efficient hunters, and there has been worry that some of our native butterfly and moth species may suffer from this new predatory pressure. The flip-side of that concern is that garden pests like cutworms and armyworms are probably being suppressed by the added predator species. P. dominula will take other insect prey, too, which allows it to be even more successful than our caterpillar-focused native species.

Adult wasps can be found nectaring on flowers, especially grape and other umbelliferous blossoms. The wasp above, imaged on the campus of the University of Massachusetts (Amherst) was chasing off all other insects attempting to visit the flower it was stationed at. This species can also damage ripening grapes in vineyards, and cherries in orchards (at least in western Colorado). Paper wasps are also very fond of “honeydew,” the sweet liquid waste products produced by aphids, scale insects, and related true bugs.

This wasp has been studied intently, and one headline-making investigation demonstrated that female dominance hierarchy in a given colony is predicated on the facial markings of the individual wasps. This does not necessarily correspond to overall fitness, though larger specimens tend to overwinter more successfully.

Only the female paper wasps survive the winter, tucked into insulated crevices where they achieve a state of lowered metabolism known as “torpor.” They then emerge the following spring to found or co-found new nests. Ultimately, only one female will lay eggs in the nest, even if another female cooperated in building the nest.

Interestingly, while most of our native paper wasp species are plagued by stylopids, the “twisted-wing insects” of the order Strepsiptera, P. dominula appears to be immune to these parasites, or nearly so. Paper wasps with what appear to be seeds wedged between abdominal segments are victims of stylopids.

There is much information about this species online, but be careful where you surf. Perhaps the most comprehensive and accurate species account is from the Identification Atlas of the Vespidae of the Northeastern Nearctic Region. A PDF article on ”Polistes dominula found in South Dakota, USA” also offers good information.

Moth Flies

It’s a moth! It’s a fly! It’s….a “moth fly!” So goes the confusion upon encountering one of the most common yet confounding dipterans. Moth flies belong to the family Psychodidae in the order Diptera. Most people have seen these diminutive, fuzzy creatures in the bathroom, perched on the side of the sink basin, or on a nearby wall. Where do they come from? Are they harmful?

The answer to the second question is easier than the first. Moth flies are not harmful, at least in the sense of public health. They do not bite, unlike their cousins the sand flies, also in the family Psychodidae, but members of a different subfamily. Sand flies not only bite, but are vectors of leishmaniasis, a parasitic disease occurring mostly in the tropics. Moth flies are mostly a nuisance, though they can reach high population densities around sewage treatment plants.

Adult moth flies are active mostly in the evening hours, and are attracted to lights after dark. Consequently, they may easily enter the home through an open door or window. While they can breed indoors (more on that later), they normally seek wet, decaying organic matter where the female can lay from 30-200 eggs in a loose cluster. Typical sites that attract them include clogged rain gutters, compost heaps, birdbaths, sewer drains, septic tanks, and filter beds at sewage treatment facilities.

I find it amusing that the scientific name of one of the most common species of moth flies, the “Filter Fly,” is Clogmia albipunctata. They certainly don’t cause clogged drains. In fact, they may be better at preventing clogs than a bottle of Draino or Liquid Plumber. This common household species can carry out its life cycle inside the pipes under your sink or shower, no matter how clean your bathroom is.

The eggs hatch between 32 and 48 hours after the female lays them, the larvae proceeding to feed on algae, fungi, microbes, and other organic matter in the gelatinous film of goo lining the average sink drain. I suspect that the many questions I receive about “worms” in the sink or shower refer to mature larvae of Clogmia that are seeking a place to pupate, or that are flushed from their normal feeding niche. It takes a larva from nine to fifteen days to reach the point where they are ready to graduate to the pupal stage. The pupa usually resides on the surface of the same organic film as the larva inhabits. An adult fly emerges from the pupa in an astounding 20-40 hours.

Moth fly larvae are actually considered beneficial organisms in the treatment of municipal sewage, so bear that in mind the next time you encounter one. You have to admire them just a little bit for capitalizing on the artificial habitats we have inadvertently created for them.

Sources: For way better images of adults and larvae, take a look at this remarkable life cycle series shot by my good friend Ashley Bradford. She is definitely not the squeamish sort! Also check out this fantastic fact sheet produced by the Connecticut Agricultural Experiment Station. It gives more detailed information than I have room for here, including how to prevent infestations and deal with existing ones.