We investigated pre-dispersal seed predation by insects in a bayberry Myrica rubra Sieb. et Zucc. (Myricaceae) on Yakushima Island, Japan. To clarify the patterns of seed fate and predation, all fruit that fell into seed traps were collected to allow any insect larvae within the fruit to emerge, and the fruit were finally dissected to determine whether or not they had been attacked by insect predators. Two lepidopteran species, Thiotricha pancratiastis (Meyrick) (Gelechiidae) and Neoblastobasis spiniharpella Kuznetzov & Sinev (Blastobasidae), emerged from the fruits. Thiotricha pancratiastis is the major seed predator of M. rubra, attacking the fruits intensively during the primary stage of fruit development. Thiotricha pancratiastis had been known as a foliage feeder (leaf miner) of M. rubra, but we revealed that the insect is also an important seed predator of the bayberry.

We explored the variable adult emergence in summer generations of a multivoltine sawfly [Arge nigrinodosa (Argidae)], larvae of which feed gregariously on the foliage of Rosa spp. (Rosaceae), and its ecological significance. The sawfly showed a trimodal adult emergence under long-day conditions in the laboratory. Following the first and largest cluster of emergence, a small tail of slightly delayed emergence was observed, which most likely was heritable. The third cluster of emergence after nonheritable partial diapause in prepupae seemed to match the synchronous emergence of a portion of adults in September under field conditions, probably as a risk-spreading (i.e., bet-hedging) strategy to cope with food shortage during unpredictable periods of drought in summer.