females tap only in response to males. A female responds within 2 seconds of a male tap. After the female responds, a male will tap again from 2 to 30 seconds later. The taps create a substrate-borne vibration. This long-distance communication mode differs from that of most wood-boring beetles, which use pheromones. To locate females, males will walk a short distance, stop and tap, orient themselves towards a female's response and repeat. If females respond they advertise their receptivity. Recently mated females will not respond. Each tapping bout contains between 4–11 taps at an average frequency of 10 Hz. Females will only respond to tapping bouts with 6 or more taps and only bouts with a frequency of 4–20 Hz. Males with higher frequencies are more likely to obtain a mate than males with lower frequencies. Mating Females have been shown to be selective of which males they mate with. During mating, males give up a significant fraction of their body mass, an average of 13.5%, via ejaculation of the spermatophore. This is a nutritional nuptial gift to the female. Although females cannot tell the mass of the male by looking at them, females can instead determine the mass of the male when the male tries to climb on the females back and mount them. Since male deathwatch beetles do not feed, their resources for the gift have been stored from the larval stage. Males who are heavier in mass are capable of donating a larger mass to the female than lighter males which results in females choosing heavier males and rejecting lighter males. By giving up this much body weight, males are reducing the likelihood that they will mate with an additional female due to a lack of resources for a further gift. Damage Due to many English buildings, especially in the south of the country, being built from old oak wood which these beetles seem to be attracted to, the greatest economic damage these beetles cause is in England. Identification of which insect is present in interior timbers is difficult; by their nature, the larvae are tucked away from sight in their galleries. The presence of wood-boring insects may be indicated by frass (fecal residue) and fresh dust. Recent exit holes often have bright rims, while the rims of older holes have become dull. The species of insects involved can sometimes be identified by examination of the fecal