Summer 1998

[TEXT ARCHIVE WEB-PUBLISHED MARCH 2002.
ORIGINAL PRINT PUBLICATION DATE: SUMMER 1998.]

Prairie walkingstick: Native grassland dweller

By Sheryl De Vore

Childhood forays into the woods or backyards in summer often reveal surprises — such as a twig that suddenly starts moving and turns out to be an interesting insect called the walkingstick.

But not all walkingsticks are the same — and there's one that you'll only find in the region's native prairies. It's called the prairie walkingstick (Diapheromera blatchleyi).

In 1907, W.S. Blatchley, an early 20th century entomologist, wrote that the prairie walkingstick "prefers rank prairie vegetation and is found throughout Illinois," in the book, Orthoptera of Northeastern America. At that time, Blatchley was one of a handful of scientists who understood about the true native prairie, says Ron Panzer, a biologist at Northeastern Illinois University who is studying walkingsticks and other insects in the region. Walkingsticks are tied to the native mesic and wet prairies of the region. Panzer said he's found them living in at least three places in the Chicago Wilderness region: Illinois Beach State Park in Lake County, Illinois, and the Indian Boundary Prairies and the Chicago Ridge Prairie in Cook County, Illinois.

As with all insects, a walkingstick possesses a head, thorax, abdomen, and six legs. A walkingstick, however, has no wings. Thus, to protect itself from predators such as birds and mice, it uses camouflage. The walkingstick's long, thin, bumpy body looks like a tree twig or a branch from a prairie forb. As the prairie grasses turn from green to brown when seasons pass from spring to autumn, the prairie walkingstick's body color changes, too.

In spring, a nymph hatches from overwintering eggs that resemble tiny black seeds and have hard protective shells. The nymph looks like a miniature adult and molts or sheds its skin several times before reaching about four inches in length. The adults then mate and the female lays eggs that will overwinter, before she and the other adults die.

Little is known about the prairie walkingstick, says Panzer. "We don't even know how many eggs the female lays, though it's probably at least 100," he says. "We do know that the eggs are laid above ground," where fire would likely destroy them. That fact presents a puzzle regarding some recent information he has gained by studying these creatures at Illinois Beach State Park.

Prairie walkingsticks are "fire positive," says Panzer. That means that fire used to restore and manage prairies has probably increased the prairie walkingstick population. Panzer says he thinks the prairie walkingstick is doing well in the region because entire areas are not burned all at once. That way overwintering eggs in an area that has not been burned develop into young walkingsticks that seem to have a penchant for recently burned vegetation. They just migrate over to the rich, nutritious emerging grasses.

Panzer is also researching a close relative, the western walkingstick (Diapheroma velei), which feeds specifically on a prairie legume called scurfy pea (Psoralia tenuflora). The plant, which grows only in small numbers at a few Chicago Wilderness sites, still thrives on hill prairies in west-central Illinois. The western and prairie walkingsticks look extremely similar, yet each has its own biological niche. As Panzer's studies continue, more may be learned about the walkingsticks that still find a place to live in our native prairies.