APRIL
2007

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

4-26-07

Insect Wings Aren't Just for Flying

The most obvious function of insect wings is for flying. Indeed the wings on insects are one of the reasons for the success of this group of organisms. Wings allow insects to escape predators, find food plants, catch prey, find mates, and move to new territories.

In a question suitable for the new game show "Are You Smarter Than a Fifth Grader" one might ask how many wings does an insect have? The correct answer is four. And two. And zero. Yes the number of wings varies depending on the species of insect, the stage of development of the insect, and in the case of ants and termites the caste.

Most scientists believe that the earliest insects were wingless. Similar to the wingless insects we know today as silverfish and collembola. Somewhere along the evolutionary trail insects began to acquire the ability to fly. Probably using a flap of some sort extending from the body or a gill that is present in some aquatic insects the insects were able to glide. Similar to the way flying squirrels use a flap of skin to glide.

At any rate somewhere in history those gliding flaps became wings attached to muscles that were used to move the wings to create lift. Today, most but not all insects have wings in the adult form. Some like the silverfish have never had wings. Others like lice and fleas seem to have lost their wings. Wings to lice and fleas are not a benefit. These insects are known as ectoparasites. Lice and fleas live on mammals and birds. Wings just get in the way as the flea or louse tries to move among the hair or feathers of the host.

In ants and termites wings are present on reproductive forms. They use wings to find mates and to move to new habitat to establish a nest. Once those activities have been accomplished the queen will chew off her wings. The wings are now useless and just get in the way as the queen moves in the underground tunnels of a nest. The wing muscles don't go to waste though. She reabsorbs the muscle tissue to feed her new brood.

Insects with wings have four with the exception of one major group. Flies have only two wings. The back wings have become club-shaped organs known as halteres. These organs function to aid the insect in stability as it flies.

While the most important function of insect wings is flight these appendages do have other functions. One such is physical protection of the insect in general and the back pair of wings in particular. Take beetles for example. The order name for the beetles is Coleoptera. Coleoptera literally means sheath wing which is in reference to the first set of wings on beetles called elytra. Elytra are shell like and provide a cover for the insect much like the shell of a turtle. The membraneous hind wings are also protected by the elytra when the insect is not in flight.

The wings of insects are also sites for coloration in insects. Think of the butterflies. These wings have the color patterns that we have come to admire. It is the scales of the wings of butterflies that provide the color. In the beautiful morpho butterflies of the rainforest regions the scales actually create the color by the angle of light reflection. So at times the insect is bright blue but when observed from another angle it appears a drab gray.

Moths, which for the most part are active at night, use the color of their wings to their advantage. The drab outer wings helps moths blend into the environment and avoid detection by moth predators. But when discovered some moths might expose the back wings which are bright colored, sometimes with eye spots, in order to startle the predator and allow the moth to escape.

Crickets use their wings to produce sound. The familiar chirp of the house or field cricket is the result of rubbing one hind wing against the other. Very much like dragging a fingernail file along the teeth of a comb.

Wings allow insects to go places, find good things, and get out of trouble. But wings also protect the insect, are a site for color and used to produce sound. To most insects a wing is a handy thing to have.

 

Writer: Tom Turpin
Editor: Olivia Maddox