Possible removal of rival sperm by the elongated genitalia of the earwig, Euborellia plebeja

Sperm displacement is a sperm competition avoidance mechanism that reduces the paternity of males that have already mated with the female. Direct anat omical sperm removal or sperm flushing is known to occur in four insect ord ers: Odonata, Orthoptera, Coleoptera and Hymenoptera. In a fifth order, Der maptera (earwigs), I found that the virga (the elongated rod of the male ge nitalia) of Euborellia plebeja seems to be used to remove rival sperm from the spermatheca (a fine-tubed female sperm storage organ). In this species, copulation lasted on average 4.6 minutes, during which time the male inser ted the virga deep into the spermatheca, and then extracted it ejaculating semen from the opening of the virgal tip. The extraction of virgae (with it s brim-like tip) appeared to cause removal of stored sperm in the spermathe ca. The virga was as long as the body length of males, and the spermatheca was twice the female body length. The long length of the spermatheca and th e possible removal function of the virga may select for virgal elongation.