Scolytidae: Tomicus piniperda male guarding female. Heads and part of thorax under bark flake of Scots pine. Only one male per female. The female bores in first and the male will fight any other males which contest him. During a fight both males stridulate (easily heard) and attempt to joust or push the rival off the tree. Stridulation is by rubbing the underside of elytra and the top of abdomen (about 1000 Hz frequencies and several pulses per second).
Byers, J.A. 1991a. Simulation of mate-finding behaviour of pine shoot beetles, Tomicus piniperda. Animal Behaviour 41:649-660.abstract button
Images © 1996 by John A. Byers, Chemical Ecology.