NOVEMBER
1996

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

11-28-96

Out Of Sight, Out Of Mind

Most of us recognize that most adult insects have wings. The ability to fly is, after all, one of the secrets to the success of the insect world. Yet some insects are very successful without wings. Fleas and lice come to mind.

Scientists believe that fleas and lice at one time had wings, but have lost them because these appendages weren't needed. Fleas and lice live on animals that are densely covered with hair or feathers. Insects can't fly in such an environment, and wings just made it more difficult to walk.

A few insects, on the other hand, never had wings. They are known as Apterygota — without wings. There are three orders of insects classified as Apterygota. Included in these orders are silverfish, firebrats and collembola.

Silverfish and firebrats are domestic species that inhabit our homes. Silverfish are gray, firebrats are tan or brown, and both have long antennae and three tail-like appendages. Silverfish prefer a moist area, so we encounter them in our bathrooms and under kitchen sinks. The firebrats, as the name suggests, like warm places, so they are found around fireplaces and furnaces. Both species are active and run rapidly.

The Collembola, on the other hand, go largely unnoticed by the human population, even though they may be the most common of all insects. They are unnoticed because they are small and live in leaf litter, damp soil or rotting logs. Most of us don't spend much time looking in these places, so we don't see collembola.

Collembola are commonly known as springtails. The name is based on the behavior of the little creature. Most species of Collembola have a forked structure on their abdomen that is folded forward and latched down. The structure is like a spring, and when released it projects the little creature forward — more like catapults it forward. Some springtails that are less than one-tenth of an inch in length may end up over 4 inches away following the release of the spring.

While most of us have never knowingly seen Collembola, there are hundreds of them in almost every handful of leaf litter. Sometimes they come out of hiding. Elliott Maynard, in his book "The Collembola of New York State," recounts reports of high numbers of these insects. In North Carolina, the numbers of one species were so high they formed blankets of insects inches thick. And in another instance, Collembola were so thick that locomotive engines in Switzerland could not move because smashed insects made the tracks too slick for traction.

Mostly, though, Collembola just quietly go about their job as one of nature's recycling crew, and hardly anyone notices.

 

Writer: Tom Turpin
Editor: Andrea McCann