APRIL
1997

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

04-10-97

Antennae Aren't Just For Space Aliens

Some people respond to insects as if they were creatures from another world. Maybe it's because they look otherworldly. The jointed legs, exoskeleton, multifaceted eyes and the antennae do give insects a far-out appearance.

To be sure, the human animal has eyes, legs and a skeleton, although somewhat different than those of insects. But when it comes to antennae, we humans have been shut out — dealt a big zero by Mother Nature.

We generally have less than an outpouring of enthusiasm for nature's creatures with antennae. That includes the insects. Maybe it's because insects wave their antennae in our faces from time to time. Or maybe it's because we're jealous that we don't have similar structures.

Actually we should be jealous. Antennae are marvelous structures that allow insects to gather information about their environment. Hairs on the antennae of some insects pick up vibrations in the air and allow the insect to hear. This is the way some male midges and mosquitoes detect their mates. The sound of the vibrating wings of the female are detected by the antennae of the male.

Both taste and smell are associated with antennae in some insects. The chemical clues detected include alarm chemicals produced by other insects of the same species. That is the reason ants very quickly come to the aid of a nest mate that has been injured or killed. Chemicals produced by female moths sometimes can be detected 5 miles downwind by a male of the same species — all because the chemical is picked up by his antennae.

In addition, insects are able to identify suitable plants on which to lay their eggs because of the odor of the plant. Many times, the plant odor is detected by sensors on the antennae. It is also the way flies find dead animals.

Some parasitic wasps actually use their antennae as a dog uses its nose, to trail another species. These wasps will tap their antennae on a surface as they attempt to follow a specific insect. When they find it, their goal is a sinister one. They will try to lay an egg on or in the creature — an egg that will hatch into a larvae, which will feed on the parasitized insect.

There are many kinds of insect antennae, and all of them have names. For instance, many grasshoppers, crickets and cockroaches have long antennae with segments that are about the same size from base to tip. These threadlike structures are called filiform and are great for waving around.

Some antennae, such as those of butterflies, have a knob on the end and are called capitate. The antennae of moths don't have a knob on the end. Instead, they generally are fuzzy, a condition termed plumose.

Some insects seem to have a flag at the end of their antennae, which are said to be lamellate. Some are bent in the middle and are called geniculate. Such is the case with ant antennae. That is good to know because that is one way to tell an ant from a termite. Antennae of termites aren't geniculate; they are more threadlike.

Whatever they are called, those insect antennae are busy picking up signals — hopefully not from outer space!

 

Writer: Tom Turpin
Editor: Andrea McCann