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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

August 1999

A well-hidden walking stick. © Don Blegen

Lithe lumber

When twigs twitch, they may be walking sticks.

Anita Carpenter

A well-hidden walking stick.

© Don Blegen

Something gently touched my shoulder as I walked through the tangled underbrush of an oak woods on a warm, late-summer day. Rather than brush it off, I glanced and sitting there as proudly as an epaulet on an officer's dress uniform, was a three-inch walking stick. I raised my hand toward the unexpected visitor. On six long, spindly legs, the insect slowly walked onto my finger. Lowering its body, it extended long, almost body-length, thread-like antennae straight ahead and froze. When I gently waved my hand, the walking stick swayed in the "gentle breeze," trying to keep its balance.

More than 2500 species of walking sticks, collectively called stick insects, inhabit the earth; most are found in the tropics. The largest present-day insect, measuring 13 inches, is a walking stick found in Borneo. My friend, Diapheromera femorata, is the only walking stick species found in the northern United States. The males may reach three inches while females grow to 3 inches.

Northern walking sticks are wingless. A small head tops an almost cylindrical body. The elongated thorax measures about half the body length (note the thorax distance between the first and third leg pairs). The abdomen is tipped with two, small sickle-shaped cerci, which are used to sense the environment.

Our resident walking sticks are slow-moving, plant-eating insects that usually feed at night on oak leaves, but will dine on hazelnut and cherry, During the day, they rest, remaining motionless for hours while posing as twigs. Their antennae and front legs stretch out rigidly before them while their hind legs may be extended backward. Their stance and cryptic coloring are so deceiving that they are difficult to find.

Young nymphal walking sticks, which hatch in spring, are green at first and pattern a maturing twig through the season, darkening to brown with each of four molts that end in late summer.

Walking sticks mate in August. A female lays her 100 eggs singly which rain indiscriminately upon the forest floor. The 3mm. oval, seed-like eggs overwinter in the ground litter. Some eggs hatch the following spring, many others take two years to hatch. The small, green nymphs must climb the oaks to feed on fresh leaves.

Walking sticks belong to the same insect order as grasshoppers (Orthoptera) but to a different insect family, the Phasmatidae. The family name is derived from the Greek word, phasm, which means apparition, an appropriate, accurate description for an insect that wants to resemble a stick. Deception is its means of survival. If found, the insect forces the discoverer to look twice to decide if it really is an insect or just a twig. Both predators and people are likely to miss the creature on second glance and continue on their journey.

Anita Carpenter keeps a close eye on nature's comings and goings near her Oshkosh home.