the male never uses it (except in the species Primicimex cavernis), instead piercing the female's abdominal wall with his intromittent organ and injecting sperm into the spermalege, a storage structure; the sperm then migrate through the female's paragenital system to reach the eggs. This practice may have evolved as males competed with each other to place their sperm closer and closer to the ovaries; the last inseminating male sires more offspring than his predecessors. Males will mount any recently-fed bug, regardless of sex, and start probing its abdomen in the region of the spermalege, thus receiving tactile, morphological and behavioral cues revealing the sex of the mounted bug. Females occasionally die from a ruptured gut after insemination; insemination via the female reproductive tract does not normally occur, except under restrictive laboratory conditions. Feeding is required for egg production in females and probably for sperm production in males. Egg-laying behavior varies among species. C. lectularius stops laying fertile eggs about 35 to 50 days after the last insemination. The American cliff swallow bug, Oeciacus vicarius, hibernates after mating in autumn and begins laying in spring, to coincide with the return of their migratory hosts. The five nymphal instars (stages) must each take a blood meal to develop to the next stage. An undisturbed bug may take 3–15 minutes to ingest a full meal depending on its life stage. They can survive long periods of time without feeding, reappearing from their hiding places when hosts again become available. Adult bedbugs have been reported to live three to twelve months in an untreated household situation. In a laboratory attempt to crossbreed a female C. lectularius with C. hemipterus males, one nymph hatched out of 479 eggs laid. It possessed features of both species, suggesting it was a hybrid instead of a product of parthenogenesis. Behavior Cimicids are attracted to hosts by a variety of cues, including heat (even a temperature difference of 1 °C) and kairomones. Host cues (at least in some species, including C. lectularius and Stricticimex antennatus) change from attractants to repellants after a cimicid has fed, causing it to move out of a danger zone after feeding. Most cimicids feed once every three to seven days in natural conditions. C. lectularius normally feeds once every seven days and Ornithocoris toledoi every eight days, though C. hemipterus has been observed feeding every day for several days (in hot climates). Excessively hot