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.

Female

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.

Male

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,” Bugguide.net.
Hojun Song. 2004. “Revision of the Alutacea Group of Genus Schistocerca (Orthoptera: Acrididae: Cyrtacanthacridinae),” Ann. Entomol. Soc. Am. 97(3): 420-435.

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,” Bugguide.net.
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.

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?

Male

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.

Female

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).

Male

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.

Female

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.”

Male

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.

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.