Entomology: Love Among the Insects

Many a studious observer has seen for himself that male insects use special tricks to woo reluctant females. Crickets and grasshoppers are musically inclined; butterflies lean to perfumes; mayflies spice up their seductions with dancing.

Zoologist Dieter Matthes of West Germany’s Erlangen University has now proved that the males of the Malachiidae, a family of tiny beetles usually found in the tropics, entice the females first with a tarty nectar, then surreptitiously slip them an aphrodisiac to loosen their inhibitions.

After a long stretch as a persistent voyeur, Dr. Matthes learned that male Malachiidae beetles have tufts of fine hair growing out of their hard shells.

In some species the tufts are on the beetles’ wing covers, in others on the insects’ foreheads. The hairs are saturated with a glandular secretion that the females find impossible to resist.

During the short mating season, a male beetle spends most of its time scuttling through the herbage searching out nubile females. When he finds one, he races in front of her, blocks her way and offers his tuft of hair as if it were a box of candy. The female almost al ways accepts the gift, leaning on the male while she nibbles the baited hairs.

The hair tuft is always offered in such a way that the female cannot nibble it without bringing her four sensitive antennae in contact with microscopic pores in the male’s shell. Through the pores seeps a subtle substance that is absorbed by the female’s antennae and affects her central nervous system, raising a wild excitement.

While the female nibbles, the male waits patiently until his aphrodisiac has had time to work. Then the male wheels around to test her reactions. If she wags her abdomen vigorously up and down, she is saying no—or at least, not yet. The urgent male gets in front of her again and feeds her more candy. Repeated feedings are sometimes necessary before the aphrodisiac administered with the candy puts her into the proper mating mood.