Factors influencing the onset of egglaying in a cecidomyiid fly

The timing of the onset of egglaying in the Hessian fly, Mayetiola destructor (Say), is influenced by several exogenous and endogenous factors. Mated females initiated egglaying 48 h earlier than virgins and laid 3–4 times more eggs before dying. The effects of mating on the onset of egglaying were further modified by several other factors whose effects were measured in hours rather than days. Increases in ambient temperatures experienced by mated females shortened the post‐mating pre‐ovipositional transition phase; however, the effects of temperature were not linear throughout the temperature range. Age of females at the time of mating also influenced the onset of egglaying. Females that mated 1 , 2 and 3 h after eclosion spent 190 , 160 and 120 min in the post‐mating transition phase, respectively. Effects of age were also observed when females were mated over the three calling periods that comprise the 3‐day lifespan of the adult female. Linear regressions of transition times on time of mating had similar slopes for first and second day post‐eclosion females but were offset such that first‐day females mated late in the morning had similar transition times to second‐day females mated early in the morning. By the third day post‐eclosion, transition times showed no significant changes when females were mated throughout the calling period. Possible mechanisms underlying the effects of mating, temperature, and female age on post‐mating pre‐oviposition transition times are discussed.