In stag beetle larvae, food availability is considered a major cause of body size variation in adults, but this has not been explicitly tested. To evaluate wood use and the effects of food quantity on growth and adult body size, the feeding performance of the tropical stag beetle Aegus chelifer MacLeay (Coleoptera: Lucanidae), which is widely distributed in Southeast Asia, was investigated by rearing larvae with different food quantities. Apparent digestibility was approximately 9%, and the efficiency of conversion of ingested food ranged from 0.7% to 1.7%. Feeding period, total food consumption, and adult body size significantly increased alongside food quantity. Males had higher consumption rates than females did at the same larval weight due to shorter food retention time. Males showed greater variation in feeding, growth performance, and adult body size than females. Differences in feeding performance that depend on food availability may enhance their fitness and may further result in sexual differences and adult body size variation.

DNA barcode analysis of specimens belonging to the genus Histeromerus Wesmael, 1838 (Hymenoptera: Braconidae) reveals the presence of two species in North America. One is identified as H. canadensis Ashmead, 1891, which is widely recorded in North America, while the other is H. mystacinus Wesmael, 1838, a species formerly known only from the western Palaearctic.