Frass-cover on Egg Masses Decreases Parasitization in the Andromeda Lace Bug, Stephanitis takeyai (Heteroptera : Tingidae)

I examined the effects of frass covering the overwintering eggs of andromeda lace bug, Stephanitis takeyai Drake et Maa, on egg parasitization by the wasp, Anagrus takeyanus Gordh et Dunbar. When the wasp was excluded by fine meshed gauze during ovipositional period, the hatchability of eggs was nearly 1.0. Therefore, if the frass cover reduces parasitization rate, it would directly increases the fitness of the mother. The estimated rate was significantly lower in egg masses covered by frass (0.72) than in uncovered egg masses (0.82). Though the egg mass size was significantly larger in the masses with cover (48.6) than that without cover (27.8), there was no positive or negative relationship between egg-mass size and parasitization rate. Therefore, at least in the winter season, parasitization by the wasp is the main mortality factor of the eggs, and frass cover on the egg mass functions as a parasitization avoidance mechanism.