Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
12/23/02
Contacts:
Donald Lewis, Entomology, (515) 294-1101, drlewis@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033,
jmcguire@iastate.edu
Yard and Garden Column for the Week Beginning Dec. 27
Sticks that Walk
By Donald Lewis
Extension Entomologist
Iowa State University
What looks like a stick and walks on six legs? That’s easy! A walkingstick!
This unusual-looking insect has to be one of Nature’s more interesting
creatures.
To those of us with a fascination for words, even the name walkingstick
is interesting. The insect name walkingstick is spelled as one word. Your
computer software spell-checking program won’t approve, but the one-word
spelling is the correct form when mentioning the insect. A walking stick
(spelled as two words) is another name for a cane or a long stick that
you use when walking.
Now with the etymology of the names of things out of the way, let’s
focus on the entomology of this interesting insect group.
A walkingstick looks like a long, slender, cylindrical stick on six spindly
legs and with two long, thin antennae. This body shape makes the insect
immediately recognizable to almost everyone, in spite of our limited opportunities
to see them. One reason we seldom see a walkingstick is its effective
camouflage. Walkingsticks, and their relatives the leaf insects, mimic
their natural background to a degree rarely matched by other insects.
Apparently, this mimicry provides excellent protection from predators
that would otherwise pounce upon these sluggish (and presumably tasty)
insects.
The other reason we seldom see walkingsticks is their preference for
feeding high up in trees. Only occasionally do they come down to our level.
The United States Department of Agriculture Forest Service has compiled
an exhaustive list of fanciful nicknames for walkingsticks. Depending
on locality a walkingstick may be called stickbug, specter, stick insect,
prairie alligator, devil's horse, witch's horse or devil's darning needle.
Most of the nicknames conjure images of malice or dread, neither of which
is necessarily true for walkingsticks in the United States.
Tropical species
There are approximately 2,500 species of walkingsticks in the world.
Unfortunately for Iowans, only four species are known from the upper Midwest
and only one species is common. Most walkingsticks are found in the tropics,
with the greatest diversity in the Asia.
Walkingsticks are herbivores. They have chewing mouthparts and eat the leaves from the tress, shrubs and other plants on which they hide. Walkingsticks are generally not considered a pest, though large populations may defoliate plants. Occasional defoliations in northern Wisconsin and Minnesota have been reported.
The species found in Iowa is known as the common walkingstick or the
northern walkingstick (Diapheromera femorata). This species is
officially named by the Entomological Society of America, the arbiter
of all insect names, as “the walkingstick.” Really. That is
its official name.
Our walkingstick is an impressive 2 2/3 to 4 inches in length. Unfortunately, it is a piker compared to some tropical species that reach almost a full 12 inches in length. All walkingsticks in the upper U.S. are wingless in the adult stage, whereas some tropical species have showy wings they can flash as further defense against predators.
The walkingstick starts life as an egg. Eggs are produced in late summer
and autumn and drop from the treetops to spend the winter on the ground.
The hard, flat, round, 1/8-inch long eggs are described as seed-like.
Even the eggs are camouflaged.
Walkingsticks have a simple life cycle. Young eggs hatch in May or early
June into 1/4-inch long, green nymphs that look like miniature versions
of the adult. Nymphs feed near the ground on the leaves of shrubs and
small trees until about midsummer when they move to the upper canopy.
There they continue feeding until they reach their final full-grown size
in late July or August. Adults are brown except the top surface that is
green or gray. Females lay eggs until frost, often producing up to 150
eggs per female.
Walkingsticks can be picky eaters. The adults prefer to feed on the leaves
of oaks, basswood and wild cherry. Leaves are eaten from other trees growing
among preferred hosts. Which include ash, paper birch, hickory, locust,
apple and chestnut. Maple trees and conifers (such as pine and spruce)
are avoided.
Household Pets
Walkingsticks, especially the large tropical species, are commonly kept
as pets in Europe. Technically, the U.S. government considers walkingsticks
to be plant pests, so exotic species are not allowed in the United States
except in registered containment facilities such as the Iowa State University
Insect Zoo. (www.ent.iastate.edu).
Common walkingsticks can be kept in captivity in a terrarium filled with an adequate food supply of fresh foliage. The adult stage may live for up to three months and breeding in captivity is possible. Ventilation is important but keep the screen top securely fastened. Like gerbils, pet walkingsticks live to “go over the wall” and see what is on the other side!
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Photo Source: http://www.insectimages.org/browse/detail.cfm?imgnum=1669026
ml: isugarden
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