none We studied the effect on the intraspecific competitive outcome of time-lags in the arrival on one host of conspecific eggs of parasitic wasps. We used three species, Dinarmus basalis, Anisopteromalus calandrae , and Heterospilus prosopidis , ectoparasitic on the larvae of azuki bean weevil, Callosobruchus chinensis . We transferred a parasite egg (occupant) onto a host in a clear plastic well, followed by another egg (invader) after a time-lag of 0, 24, 48, 72, or 96 hours. This enabled us to observe directly the competitive process occurring between the wasp larvae on the host. All three wasp species showed "contest" type larval competition, in that competition almost always resulted in the emergence of only one wasp offspring from one host regardless of the initial egg density per host and time-lag. However, the competitive outcome depended on the interval of time-lag of two ovipositions.