APRIL
1993

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

04-22-93

That's about the size of it

One of the reasons for the success of insects is their small size. Because they are small, insects can crawl into and live in places other animals can't. Being small also means it takes less food to survive, and it is easier to hide from enemies.

Just how small are insects? The smallest insects are less than a silly millimeter in length. Insects known as hairy-winged or feather-winged beetles are little bitty things. They get their name because their hind wings are fuzzy and the largest of the beetles are less than 1 millimeter in length. Some are only a silly half millimeter long. They are so small they can easily go through the eye of a needle.

Other small insects include wasps that are parasites of insect eggs. These include the trichogramma, some species of which are reared and released to control harmful insects in biological control programs.

Another egg parasite is a wasp known as a fairyfly. One fairyfly has a body of just two-tenths of a millimeter in length. It would take over one thousand of these wasps lined tail to antennae to cover an inch.

Even the largest of the insects aren't large compared to other animals on the earth. The largest insects by weight are even named after large creatures. The Goliath beetles of Africa and the elephant beetle of South America are the heaviest insects. These insects weigh more than 2 ounces and are larger than the smallest birds and mammals.

The longest insect is probably a stick insect of Australia which is 10 inches long. The Atlas moth of India and the Great Owlet moth of South America have wing spans of 11 to 12 inches. Queen Alexandra's birdwing butterfly of New Guinea has a similar wingspan.

The largest insects are no longer present on the earth. They lived at the time of the dinosaurs and, like their earthmates of the time, have ceased to exist. One of the largest of the extinct insects was a dragonfly that had a wingspan of over 2 feet.

Time has proven that small is better for the insect way of life. Indeed, for many insects a good strategy for survival is “out of sight, out of mind.” Small biting midges known scientifically as Ceratopogonidae are good examples. These insects are blood suckers with a vicious bite. Their small size and quick escape habits have given them the name “no-see-ums!” You generally don't see-um and by the time you feel-um it's too late because they are gone!

 

Writer: Tom Turpin
Editor: Andrea McCann