INTRASPECIFIC VARIABILITY IN THE TAPPING BEHAVIOR OF THE DEATHWATCH BEETLE, XESTOBIUM-RUFOVILLOSUM (COLEOPTERA, ANOBIIDAE)

Taps were recorded from 46 male and 30 female deathwatch beetles, Xest obium rufovillosum. Beetles tap by striking the frons of the head on t he substrate 4-11 times, at a frequency of about 11 Hz. There were no significant differences between the sexes in the number of strikes per tap, or in the frequency of the strikes, although there was significa nt variation between individuals of both sexes in both of these parame ters. Males usually initiate a sequence of taps, to which females repl y. Females responded more readily to male beetle taps containing high strike numbers. Use of an artificial tapper showed that females respon ded most to taps containing at least six strikes. Females did not disc riminate between male beetle taps on the basis of strike frequency, al though at abnormally high (20-Hz) or low (4-Hz) frequencies produced b y the artificial tapper, females were less likely to respond. Male bee tles located the source of taps from the artificial tapper and did thi s more readily with taps of a high strike number. It is not clear why some males produce taps with fewer than six strikes, as these are unli kely to elicit a female response, and so should be the subject of adve rse sexual selection.