There are several hypotheses as to the function of postcopulatory mate guarding. Control over the mate‐guarding period by either sex could potentially influence relative reproductive success. Mate‐guarding behaviour in Gryllodes sigillatus was studied under several conditions: 1. undisturbed pairs; 2. pairs with a single male intruder; 3. pairs exposed acoustically, visually and olfactorily to several other males; 4. pairs exposed freely to several other males; and 5. pairs exposed freely to several other females. The results provide support for the spermatophore retention and rival defence hypotheses. The efficacy of mate guarding was not compromised by the pair being in acoustic, visual and olfactory contact with several other males. Once pairs were exposed to free contact with several other males, the spermatophore retention time by the female declined significantly, indicating that the mate guarder’s efficiency declines under competition from several rivals. In pairs exposed to contact with several females after mating, the mate‐guarding period and spermatophore retention time declined as the mate guarder abandoned the mated female and pursued the other females. Termination of the effective mate‐guarding period by either sex seems to be influenced by the number of other potential partners present.