Friday, December 20, 2013

House Flies

Happy “Fly Day Friday,” dear reader, and Happy Holidays, too. I hope you don’t have to share the leftovers with household pests, but I thought you might enjoy learning a little about one of the more common “guests” you could be entertaining at almost any time of year: The House Fly, Musca domestica, in the family Muscidae.

Naturally, house flies are most abundant during the warmer months, and you are unlikely to encounter them in the dead of winter unless you live in our southerly latitudes, and/or in a rural area. In fact, the House Fly is more common around farms, ranches, zoos, and stockyards than anywhere else. Why? A favorite food of House Fly larvae is horse manure.

Here in Colorado Springs, where your neighbor up the street might have a pony, we see more house flies than you might expect for an urban area. We don’t see them now, though, despite what some people may claim. The problem is one of mistaken identity. Several other flies are commonly mistaken for the House Fly.

House flies are not very large, measuring a mere 6-7 millimeters in body length. They are overall dull gray with beige or yellowish flanks (the sides of the abdomen). They have white faces with large, dark eyes. Those eyes converge and nearly meet at the top of the head in male house flies, while the eyes are farther separated in females.

House flies are smaller than most other flies they can be confused with. Many kinds of blow flies in the family Calliphoridae overwinter as adults and can be seen on sunny winter days basking on the south-facing exterior walls of buildings. Calliphorids are robust, and often metallic to some degree, especially on the abdomen.

Blow Fly

Flesh flies of the family Sarcophagidae sport bold, black stripes down the top of the thorax. They also have scarlet eyes and “tails,” the tip of the abdomen being red, most noticeably so in males. Both flesh flies and blow flies are usually more abundant in urban areas than house flies are.

Flesh Fly

Heleomyzid flies are about the same size as house flies, but appear more slender with longer, narrower wings. These “sun flies” do appear in late autumn and early spring, sometimes indoors. Note the row of setae (hair-like spines) on the leading edge of the wing that distinguishes heleomyzids from similar flies.

Heleomyzid Fly

House flies groom fastidiously, for keeping clean allows them to more quickly notice and evade the swatter. Watch one and be amazed at the gymnastic maneuvers it goes through to shine its wings and polish its eyes. The devious personality we assign to these pests is no doubt heightened when they rub their front feet together like a vintage movie villain wrings his hands while generating a fiendish plot.

Despite their personal hygiene, there is no question that house flies are mechanical vectors of many pathogens that cause illnesses as mild as diarrhea or as serious as typhoid fever. It should be noted that the House Fly has mostly been implicated in the transmission of diseases. Still, house flies don’t discriminate between something edible and something that has already been eaten and passed out the other end.

House flies pass through complete metamorphosis and can go from egg to adult in as little as two weeks time under optimal conditions. There can be ten or twelve generations annually in temperate climates. The female lays batches of 75-150 eggs in a three or four day period, depositing the ova in a food source. Horse manure may be a preferred food, but any decaying organic matter suffices for breeding these insects. A maggot molts only twice after hatching from the egg, the third molt resulting in the pupal stage. The pupa is encased in a capsule-like shell that is the last larval “skin.”

Proper sanitation is the best way to keep house flies at bay, but some people swear by the simple technique of hanging a clear Ziplock baggie, half-filled with water, on the outside of a screen door. Scientists have largely dismissed this trick as hogwash, but experiments haven’t established conclusive proof one way or the other (Mikkelson and Mikkelson, 2013).

House flies are found pretty much the world over, but apparently the species originated in the steppe regions of interior central Asia. Livestock traffic and other commerce no doubt spread the fly far and wide long ago.

Oh, back to the flyswatter. Wonder why you are seldom successful? Flies, like many insects, perceive motion much better than people. It is said that a House Fly would see a motion picture as a series of still images. Your best technique for nailing one of these pesky critters is to sl-o-o-o-wly lower your weapon to within a few inches of the target, then quickly slap it down….Yeah, good luck with that.

Sources: Berenbaum, May R. 1989. Ninety-nine Gnats, Nits, and Nibblers. Urbana, IL: University of Illinois Press. 263 pp.
Sanchez-Arroyo, Hussein, and John L. Capinera. 2008. “Common Name: House Fly,” Featured Creatures, Entomology & Nematology, University of Florida
Mikkelson, Barbara and David P. 2013. ”Fly Bye,”

Wednesday, December 18, 2013

Eastern Cicada Killer

Mowing the lawn one August day, Jim noticed saucer-sized piles of soil in the bare patches, with a large hole on the edge of each one. He figured it was the work of rodents until he saw an enormous wasp enter one of the holes dragging another large insect behind it. Jim decided to avoid that part of the yard.
This scenario, and others like it, plays out over much of the eastern United States during the summer, creating mystery, annoyance, or downright hysteria for those finding that the Eastern Cicada Killer, Sphecius speciosus, has taken up residence on their property.
A Community of Killers
Cicada killers are solitary. This means that each female wasp excavates her own nest. Many wasps may burrow in the same area, creating the impression that they are giant, social yellowjackets or hornets. Male cicada killers, while incapable of stinging, will drive off other males, other insects, even birds as they seek mating opportunities with females. They sit on the ground, or foliage, rocks, or other objects that give them a somewhat elevated perch from which to survey their territory. Watch them cock their heads alertly at the passing of other wasps.
The female digs her burrow before she starts hunting. The tunnel extends up to three feet, at a depth of two feet. Individual cells branch off near the end of this shaft. Each “room” will host one of her offspring.
The Eastern Cicada Killer hunts mostly “annual” or “dog-day” cicadas in the genus Tibicen. These large, loud insects are heard in the tops of deciduous trees during July and August. The female wasp flies into the canopy and combs each branch until she bumps into a cicada. She grabs the insect and stings it into paralysis. A “shrieking” cicada is likely being attacked by a cicada killer.
The Cicada Killer Life Cycle
Cicada killers are strong. A wasp may fly directly from the scene of the crime back to her burrow, carrying her prey beneath her. Sometimes the journey is accomplished in stages, gliding from the tree to the ground, up another vertical object to launch another short flight, and so on until she gets home. She has to hurry: birds often harass cicada killers into dropping their prey.
She dives down the entrance to her burrow, hauling her prize to one of the underground cells. One cicada is enough to grow a future male cicada killer, but a baby (larval) female cicada killer needs to eat at least two cicadas, sometimes three. The mother wasp lays a single egg on the last cicada put into a cell. When all cells are filled, she fills the nest entrance and leaves permanently.

Typical cicada used as prey
The cicadas are paralyzed, not dead, which prevents them from spoiling until the wasp larva finishes consuming them. The egg hatches in a day or two, and the larva starts feeding. It matures quickly, in an average of ten days. The larva then spins a silken cocoon, incorporating soil particles into the capsule. Inside that covering it turns into a pupa, the externally inactive stage of metamorphosis. Pupae overwinter within their respective cells, the adult wasps chewing their way out the following summer and beginning the cycle anew.
Fueling up
Both male and female cicada killer wasps feed on substances rich in sugars and carbohydrates to fuel their energetic activities. Look for them on flowers where they sip nectar. Also look for them eating oozing, fermenting sap on the trunks of trees. Some of the images shown here depict this behavior. I even gently nudged one of the big female wasps into a better position while I was taking pictures.
Cicada killers are probably the largest, bulkiest wasps you are likely to see east of the Rocky Mountains from Massachusetts and southern Ontario to Florida and Texas. The adult wasps range from 30-40 millimeters in body length, though some females can be up to 50 millimeters (just shy of two inches). No wonder they can seem so intimidating.
Nothing to Fear
Solitary wasps will not sting unless physically molested, or you step on one in bare feet. Male wasps may behave aggressively, but they lack a stinger.
Should you be fortunate enough to have cicada killers in your garden, enjoy watching the drama of their lives. The adult wasps live only 2-6 weeks, so the phenomenon of their nesting is fleeting.
Sources: Holliday, Charles. 2012. “Biology of Cicada Killer Wasps,” Prof. Chuck Holliday’s www Page at Lafayette College.
O’Neill, Kevin M. 2001. Solitary Wasps: Behavior and Natural History. Ithaca, NY: Comstock Publishing Associates (Cornell University Press). 406 pp.
Shapiro, Leo, et al. 2012. “Sphecius speciosus: Eastern Cicada Killer,” Encyclopedia of Life.

Saturday, December 14, 2013

"Albino" Bugs

I am frequently presented with descriptions or images of what people assume are “albino” insects. Usually, the specimens are clearly lacking pigment. The mistake is understandable, but there is precious little information widely available to explain what is actually going on. Allow me.

As far as I am aware, there is no such thing as an albino insect, spider, or other arthropod. Aside from some species endemic to caves where there is no sunlight, there are no species permanently devoid of pigment. What people are finding are specimens that have recently molted. In the immediate aftermath of shedding its exoskeleton (“skin”), an insect is generally soft, wet, and white, eventually hardening, drying, and darkening. The newly-minted adult American Cockroach shown above is a typical example. Note the slightly darker individual at bottom that had molted hours earlier.

Molting is known as ecdysis in scientific lexicon. It is a highly complicated process that is governed largely by hormones, and makes possible the astonishing transformations known as metamorphosis.

We came to learn of the complexities of insect development through the diligent work of physiologists that commenced around the early 1920s. Some rather primitive and grotesque experiments by Stefan Kopec in Poland demonstrated that just prior to molting the insect brain sends a signal to the prothoracic gland which in turn produces molting hormones called “ecdysones.”

Ecdysones are actually steroidal hormones. Their levels are elevated suddenly before molting, triggering a cessation of feeding and stimulating gene expression (and/or suppression?) that will apply to the next stage of development.

Many freshly-molted true bugs are pink

The presence of another hormone called “juvenile hormone” means that the next developmental stage will be another larval or nymphal instar. The absence of juvenile hormone (JH) in the haemolymph (insect blood) signals transition to the pupa or adult stage, whichever applies. JH is also important in reproductive biology in the adult male insect, even though its effects are dormant during metamorphosis.

Back to the actual process of molting. Epidermal cells begin manufacturing a new exoskeleton, while at the same time enzymes are liberated into a “molting fluid” that erodes the inner layers of the old cuticle, making those amino acids and sugars available for recycling into the new exoskeleton. Muscle attachments to the old cuticle are actually broken through rhythmic contractions of the insect’s body from back to front.

Cicada molting to adulthood

The old cuticle splits along predetermined ecdysial sutures, kind of like the perforations that allow you to easily open a box. As the insect extricates itself from the old exoskeleton, a waterproofing substance is deposited atop the new cuticle. This material is secreted by dermal glands.

Once the insect is free of the old “skin,” it takes in air to literally inflate itself to a larger size while the new cuticle hardens. This hardening process takes hours if not days, and is called “sclerotization.” This process begins prior to molting in the jaws (and sometimes other body parts like the crochets on the prolegs of caterpillars).

Insect larvae have a thinner, more flexible exoskeleton than nymphs, pupae, and adult insects. Therefore they are often not as densely pigmented. The shed exoskeleton of a larva with chewing mouthparts is often consumed by the insect itself so as to recycle the nutrients and eliminate evidence of its presence to keen-eyed birds and other predators that are alert to such signs of insects.

People who find the shed exoskeletons of insects may think that the ghostly objects are actually living specimens. The durability of shed exoskeletons is indeed astounding. Cicada shells may remain affixed to trees and other vertical objects for months after the adult insect has lived and died. Oh, and those stringy white things protruding from the seam where the insect emerged? Those would be the remains of major tracheae. Yep, even the tracheae of insects is sclerotized.

A shed exoskeleton is called an "exuvia," plural "exuviae"

Considering how vulnerable insects are during, and immediately after, molting, it is amazing how many survive to adulthood. Predators can get them while they are soft and immobile. They can become hopelessly entangled. Yet, here they are, the most successful and abundant of all organisms.

Sources: Hadley, Debbie. 2013. “How Insects Grow – The Molting Process,”
Mills, Erin. 2011. “In My New Skin,” Beyond Bones blog, Houston Museum of Natural Science
Resh, Vincent H. and Ring T. Cardé (Eds). 2003. Encyclopedia of Insects. San Diego, CA: Academic Press (Elsevier Science). 1266 pp.

Thursday, December 12, 2013

The Obscure Bird Grasshopper

The Obscure Bird Grasshopper, Schistocerca obscura, might be better named the conspicuous bird grasshopper, for it is one of the larger and more eye-catching of its kind. An adult male can be 36-45 millimeters in length, while females can reach a whopping 50-65 millimeters (2-2.5 inches). They may startle you by exploding into flight from grasses and shrubs, as they are alert and quick to depart the scene if discovered.


I had the privilege of encountering numerous specimens this fall when my wife and I visited the Prairie Center (Olathe, Kansas), and Leavenworth, in late September. Indeed, all the images here were taken on September 21.

This species is related to the famed Desert Locust, Schistocerca gregaria, that periodically makes headlines for its near apocalyptic swarms in Africa and southern Europe. S. gregaria is the sole Old World representative of the genus. We have ten species in North America, as of the most recent revision of the genus.

The term “locust” correctly applies only to the migratory phase of a few species that are normally solitary. Overcrowding in the nymph stage is what triggers the change. Nymphs literally rub elbows (er, “knees”?) while marching overland, and this constant jostling stimulates hormonal changes that lead to an adult stage that is more streamlined, with proportionately longer wings, than the average member of its species.

Locust swarms number in the millions if not billions, and while the insects themselves are powerful fliers, they also take advantage of storms, riding the winds ahead of fronts. When they settle, almost anything is fair game for their diet, including dead and dying members of their own kind. Most species in the order Orthoptera are, in fact, ominovorous.

Fortunately, The Obscure Bird Grasshopper and its New World relatives are rarely populous enough to be so destructive to agriculture. That is not to say that they do not migrate. They are capable of long distance seasonal migrations that can take them outside of their normal ranges. S. obscura is widespread in the eastern U.S., from Maryland south to Florida and west to Kansas, Texas, and even parts of New Mexico and southeast Arizona (south through most of Mexico). While it has been documented as far north as Pennsylvania and Nebraska, its roots are in the south and those northerly records are mostly a result of seasonal migrations during favorable years.


Several other species in this genus may closely resemble the Obscure Bird Grasshopper, and it is necessary to examine the tip of the male’s abdomen to make a concrete identification. The preferred habitat of this species is open woodlands, which contrasts a little with look-alike species. Adults can be found from July through September, a little earlier and later in the most southerly latitudes.

If you have trouble differentiating all the Schistocerca anyway, take heart. Species and subspecies delineations are still being debated among experts. Just count yourself lucky if you happen upon a population or migration of these stunning insects. They literally don’t come around that often.

Sources: Capinera, John L., Ralph D. Scott, and Thomas J. Walker. 2004. Field Guide to Grasshoppers, Katydids, and Crickets of the United States. Ithaca, NY: Comstock Publishing Associates (Cornell University Press). 249 pp.
DiTerlizzi, Tony, et al. 2011. “Species Schistocerca obscura - Obscure Bird Grasshopper,”
Hojun Song. 2004. “Revision of the Alutacea Group of Genus Schistocerca (Orthoptera: Acrididae: Cyrtacanthacridinae),” Ann. Entomol. Soc. Am. 97(3): 420-435.

Tuesday, December 10, 2013

Grand Western Cicada

On this “True Bug Tuesday,” with Christmas carols seemingly always within earshot, I harken back to summer and the melodic sounds of cicadas. Ok, maybe “blaring noise” is a truer description of those members of the genus Tibicen that were omnipresent during our visits to Ohio, Iowa, and Kansas this year. One of the more impressive species we saw was the “Grand Western Cicada,” Tibicen dorsatus.

T. dorsatus is also known as the “Bush Cicada” and “Splendid Prairie Cicada.” Indeed, it is most abundant in remnants of tallgrass and shortgrass prairie, and savannah-like habitats in the Great Plains states east of the Rocky Mountains and west of the Mississippi River. Scattered records are also known as far east as Indiana. Few populations exist north of Wyoming and southern South Dakota.

This species is one of the so-called “annual” cicadas. That term translates to at least some individuals of a given species emerging as adults every year, even though the life cycle still takes about five years or more to complete. So, emergences are staggered, not synchronized as is the case with the periodical cicadas of the genus Magicicada. Annual cicadas also emerge later in the season than their synchronous relatives. Look for T. dorsatus in July, August, and September (as early as June in some southern latitudes).

The fact that annual cicadas are frequently heard during the hottest part of the summer and fall has lent them additional labels of “dog day cicadas” and “harvestflies.” They also present themselves during the hottest times of the day, depending on the species, adding a literal, audible sizzle to the infernal temperature.

Only male cicadas produce sound, and they do so internally. Most of the abdomen of a male cicada is occupied by two large cavities, each opening on the underside but covered by a lid-like “operculum.” Inside, a large muscle in each chamber can be vibrated at high speed, producing a sound that is amplified and projected outward as the insect contorts its body. The Little Drummer Boy has nothing on these guys.

Most of a cicada’s life is spent underground, of course, living as a hunchbacked nymph sucking plant sap from roots of trees and shrubs and other plants. That diet doesn’t foster rapid growth, and it therefore takes the insect a long period of time to mature. Eventually it does so, though, and claws its way to the soil surface, usually under cover of darkness, to complete its metamorphosis.

As soon as the nymph extracts itself from the ground, it seeks in earnest the nearest vertical object. Climbing to an adequate height (perhaps an individual decision rather than a hard-wired instinctive one) it digs in and splits its exoskeleton down the middle of its back. A soft, pale insect with stubby wings pulls itself out with great effort.

Many cicadas must perish in the act of this final molt, becoming tangled in their own “skin,” or simply not having enough energy to complete the ordeal. Others come out imperfect, unable to fly or with malformed legs. Those that do manage to struggle out of their old selves then hang quietly while the wings inflate and pigments begin to manifest themselves in the otherwise ghostly creature.

Once hardened, cicadas are durable insects. I once saw a Blue Jay catch a cicada in Cincinnati, Ohio, try to hammer it to death on a utility wire, only to have the insect slip out of its beak and fly away.

The Grand Western Cicada is one of our larger species, measuring around 57 millimeters (2.5 inches) from “nose” to the tips of its folded wings. The decorative white markings are actually waxy, and can rub off. The waxy substance also covers the belly of the insect, and cicadas often orient themselves belly-up to the sun so as to prevent becoming overheated.

While many cicada species also call from the canopy of trees, where they are shaded, the Grand Western Cicada often perches low on vegetation where it tends to be more exposed. Despite its contrasting coloration, it is surprisingly cryptic.

Another, very similar species, Tibicen tremulus, has recently been described. Its range overlaps with that of T. dorsatus, and the only way to easily segregate the two in the field is by differences in their songs.

This last summer was apparently a good year if you like cicadas. They were very abundant in the Midwest U.S. If you missed their diversity and concerts, keep an ear cocked for them next year.

Sources: Bartlett, Troy, et al. 2013. “Species Tibicen dorsatus - Bush Cicada,”
Cranshaw, Whitney, and Boris Kondratieff. 1995. Bagging Big Bugs: How to Identify, Collect and Display the Largest and Most Colorful Insects of the Rocky Mountain Region. Golden, CO: Fulcrum Publishing. 324 pp.
Hill, Kathy, and David C. Marshall. 2013. Insect Singers.
Salsbury, Glenn A. and Stephan C. White. 2000. Insects in Kansas (3rd Edition). Topeka, KS: Kansas Department of Agriculture. 523 pp.

Sunday, December 8, 2013

Pantropical Jumping Spider

This week, if you live pretty much anywhere north of Mexico, a tropical vacation sounds pretty appealing. Well, if you were a Pantropical Jumping Spider, Plexippus paykulli, you would probably be enjoying yourself right now. This species is a world traveler, now dispersed to most tropical and subtropical climates across the globe. Envious?


The Pantropical Jumper is pretty easy to find, too, since it hangs out on the exterior of buildings where it can be quite conspicuous. The only problem might be telling it apart from the Gray Wall Jumper which is often seen on buildings, too. Both species are of similar size. Adult females of the Pantropical Jumper are 10-12 millimeters in body length; males average 9.5 millimeters.


Plexippus paykulli is also sexually dimorphic, meaning that the male gender looks radically different from the female sex. In fact, it would be easy to assume they are two different species. This is typical of many jumping spiders: the males are adorned with colorful scales, or tufts of hair on their legs and/or pedipalps which are used to communicate with the female through elaborate displays, often accompanied by vibrations carried through the substrate (surface on which the spiders are sitting).


Pantropical jumpers don’t sit on the beach sipping fruity drinks. Nope. They actively seek prey by day, including small moths, flies, flying ants, and even other spiders. They have the typical behavior of most jumping spiders in the family Salticidae, running a short distance, pausing, pumping their pedipalps up and down, and turning to face whatever piques their curiosity (or perceived threat).

Mated females of this species spin a small, flat egg sac about nine millimeters in diameter that contains anywhere from 35-60 eggs. A larger silken envelope, 25-35 millimeters around, covers the egg case and serves as a retreat for the female to guard her future offspring. Look for these nurseries under eaves of buildings, in cracks and crevices, or under boards and other objects.


Here in the United States, Plexippus paykulli can be found year-round in South Carolina, Georgia, Florida, the Gulf Coast states, and south Texas. Outlying populations in New Mexico, and north along the Atlantic seaboard are probably the result of accidental introductions. You are also likely to see this spider in such exotic locales as Hawaii, Hong Kong, India, Greece, and parts of Africa. It is assumed that the species is native to southeast Asia.

The Pantropical Jumping Spider should be considered an asset to any resort, hotel, or motel, for they are literally a mobile pest control service. They are known to hunt mosquitoes and small cockroaches among other pests. I guess you would call that a “working vacation.”


Sources: Bradley, Richard A. 2013. Common Spiders of North America. Berkeley: University of California Press. 271 pp.Edwards, G.B., Jr. 2002. “Jumping Spiders,” Featured Creatures. Division of Plant Industry and University of Florida.
Gaddy, L.L. 2009. Spiders of the Carolinas. Duluth, MN: Kollath+Stensaas Publishing. 208 pp.
”Pantropical Jumper,” iNaturalist.

Friday, December 6, 2013

Fly Day Friday: Snow Flies

As I write this, the outdoor temperature here in Colorado Springs is a whopping 5° F. There are going to be few, if any insects out and about in those frigid conditions. A sunny winter day, even higher up in the mountains, could provide a different story. There are wingless crane flies that can be seen crawling across the snow in the dead of winter.

Last October 27, 2012, I was fortunate enough to take a trip with other members of the Aiken Audubon Society to Guanella Pass (Clear Creek County) in search of ptarmigans. We got skunked on the birds, but one person in our party spotted a tiny insect creeping across the snow. I instantly recognized it as a wingless crane fly, though I had only seen images of them until then.

There are sixteen species of “snow flies” in the genus Chionea in North America. They are in the crane fly family Limoniidae, formerly a subfamily of the Tipulidae. While western species are mostly confined to mountain ranges, eastern species can be found in most forested areas, especially in regions that experienced glaciations during the most recent ice age. They appear most commonly in October and November, and again in February and March.

While these dark flies are most conspicuous on the surface of the snow, most of the time they are concealed in the tunnels of small mammals, beneath leaf litter, or fairly deep in caves. These situations help to insulate them from truly severe weather, and an adult snow fly may live up to two months.

Drawing by Dr. George Byers

The life cycle of Chionea remains mostly a mystery. Every attempt to rear them in the laboratory has failed because no one knows what the larval stage feeds upon. We do know that an adult female fly can produce up to 194 eggs, each one laid singly. Lacking wings, the female fly can store eggs even in the thoracic cavity that is normally packed with wing muscles.

Eggs take eight days to three weeks to hatch under laboratory conditions. Larvae have fairly hardened mouthparts, suggesting they may be able to take in solid food. Just what that nourishment could be is up for conjecture. Maggots of distantly-related flies feed on fungi that grow on bat guano in caves, but that information may or may not be relevant to snow fly larvae. We do know the larvae feed and grow during the summer months, with pupation taking place in the fall.

Adult snow flies have few enemies, but we know that mice are among their predators. Believe it or not, this conclusion is reached from knowledge of the cycle of parasitic tapeworms. Rodent tapeworm eggs expelled in the feces of a mammal must be consumed by an insect, usually a larva. Once inside the insect, the tapeworm metamorphoses into a “cysticeroid” stage. There it remains until the insect is in turn consumed by a rodent. Tapeworm eggs have been found in the gut of adult snow flies.

Rock-crawlers, primitive insects related to mantids and cockroaches, are also predators of snow flies. Grylloblattids, as rock-crawlers are known in the scientific community, are found in isolated populations at high elevations in western North America.

How do snow flies keep from freezing to death? First, snow flies occupy the “subnivean” environment: a microclimate that exists in cavities beneath the snow created by arching grassblades, leaf litter, and rodent tunnels. These nooks and crannies offer protected niches with temperatures that are milder than the surface and air temperatures above.

Snow flies also have a body chemistry to cope with the cold. Many insects have glycerol in their body fluids, which acts as an antifreeze, preventing the formation of sharp, life-threatening crystals of ice inside the insect’s tissues. Differing enzyme systems also allow snow flies to function at lower temperatures than most insects. In fact, they are susceptible to overheating!

The temperature in the room where I write this is not that warm, either. I am not believing the 66° registered on the digital thermometer and, lacking my own internal antifreeze, will go open a can of soup. Stay cozy, friends.

Source: Schrock, John R. 1992. “Snow Flies,” Kansas School Naturalist 38(2): 1-16.

Wednesday, December 4, 2013

Ichneumon Wasp: Ceratogastra ornata

Welcome to "Wasp Wednesday." The wasp family Ichneumonidae is one of the most diverse in the order Hymenoptera, especially in the largely temperate climate of North America. Many species look superficially alike, even if they belong to different genera. One of the few species I can usually identify in the field is Ceratogastra ornata, which I still often mistake for a spider wasp anyway.

This wasp is well-named, for it is ornately patterned with yellow and reddish brown or black, depending on the geographic location where one finds them. In fact, four subspecies are recognized. Collectively, they are distributed from southern Ontario, Massachusetts, and southern Wisconsin west to eastern California and south to northern Florida, Louisiana, and Mexico.

Specimens from the northern reaches of the species’ range are generally darker, including the wings, with reduced yellow markings. Specimens from farther south and west, like the one shown here from Colorado Springs, are distinctly paler.

It has been suggested that this wasp is a mimic of stinging spider wasps in the genus Poecilopompilus. Indeed, the similarities in color and pattern are striking, though the spider wasps are slightly larger than the ichneumon's 10-12 millimeter body length in most cases. Here in Colorado Springs, I found another spider wasp, Ceropales, to be a potential model for the ichneumon.

Ceropales sp.

How do you tell the ichneumon wasp from the spider wasp it mimics? Look at the antennae for one clue. Ichneumon wasps have many, short antennal segments while spider wasps have far fewer, and longer, segments. Wing venation offers other characters, but one seldom gets a good look. Images of ichneumons may capture the “horse head” cell near the middle of the front wing, the horse’s “nose” pointed toward the wingtip.

Look for Ceratogastra ornata visiting flowers, especially composites. They are not only seeking nectar, but hosts for their larval offspring as well. You might see a wasp that appears to be stinging a flower bud, but this behavior is aimed at the eggs of a moth instead.

Details are sketchy, but apparently females of some moths in the genus Feltia (family Noctuidae, the owlet moths) lay their eggs in certain flowers. The caterpillars that hatch then migrate to the ground where they finish their life cycle as subterranean “cutworms.” The ichneumon wasp intercepts the egg stage, or newly-hatched caterpillar, injecting her own egg into the host. Her larva lives as an internal parasite of the caterpillar, likely letting it mature before feeding in earnest and ultimately dooming its host.

I have personally witnessed female Ceratogastra ornata ovipositing in buds of Common Ragweed, Ambrosia artemisiifolia. The entomologist J.C. Bridwell has also observed this, and found them ovipositing in Eupatorium thoroughworts as well. The wasps also visit goldenrod flowers, but are not known to oviposit among the blossoms (Carlson, 2009). The specimen shown here was favoring the extrafloral nectaries of Common Sunflower, Helianthus anuus.

The inability to identify ichneumon wasps to species should not be a barrier to observing them, or even collecting them. We know precious little about the biology and geographic range of the majority of species. Your images, posted to, could shed light on this interesting group. Bob Carlson, a world authority on Ichneumonidae, often offers his expertise there as well.

Sources: Carlson, Robert W. 2009. “Database of Hymenoptera in America North of Mexico,” Discover Life
Eaton, Eric R., et al. 2011. “Species Ceratogastra ornata,” Bugguide.

Monday, December 2, 2013

Post 400

Dendroctonus sp., © Eric R. Eaton

I can hardly believe I have reached this milestone of a 400th post on this blog. When I started way back in February of 2009, I faced many unknowns. Would I have the discipline to write regularly? Would anyone read the posts? Back then, I knew nothing of social media, and hadn’t even started taking my own images.

There have been many life changes along the way, too. I became unemployed, employed irregularly and temporarily, and am now unemployed again. I met a wonderful woman, moved to her city, got married, and combined households. I have traveled fairly extensively, accruing images as I go.

My major goal in creating a blog was to help educate the general public about insects, arachnids, and other arthropods. I am still unsure if I am only “preaching to the choir,” but Facebook (and now Twitter) have helped extend the reach of this blog. As of yesterday, I was ranked number seven for invertebrate blogs on the Nature Blog Network (and #83 for all blog subjects).

What of the future of this blog? Expect it to continue. Do not expect me to move to WordPress. I find the interface to be horrible for me as a writer. I know this means you cannot easily view the blog on mobile devices; I know some complain that they cannot post comments. My apologies for that, but these are problems with Blogger, not me. Why they are not more responsive is beyond my comprehension.

You can expect more, and more frequent, content during the winter months when I am traveling less and spending less time in the field. You can always make requests for blog topics. I will gladly research and write about the subject you wish to know about, provided I have images, or you have some you can share to illustrate the topic.

“Spider Sunday,” “Moth Monday,” “True Bug Tuesday,” “Wasp Wednesday,” “OrThoptera Thursday,” and “Fly Day Friday” will continue to be irregular features, with a total of roughly two or three blog posts made each week. Whenever possible, I want to include images of the immature stages, especially for moths, but I have few identified caterpillar images of my own at present, perhaps even fewer that correspond to my images of moths.

So, this blog will continue, but is subject to change depending on what you, the audience, wants out of it. I welcome your suggestions, criticisms, and complaints, as always. Feel free to e-mail me if you cannot comment directly. Thank you. BugEric24ATyahooDOTcom.