Several kinds of larvae feed by tunneling into and within cones. Characteristically, pellets of frass (ex-
crement) are deposited within or on the cone, often mingled with obvious strands of silken webbing. Attacked cones are easily noticed because all or parts of the cones turn brown. Such cone-damaging insects belong to two moth families, the Pyralidae (Dioryctria spp.) and the Olethreutidae (Eucosma spp.), and one beetle family, the Scolytidae (Conophthorus spp.). Several genera of midge flies in the family Cecidomyiidae also kill or damage cones by less obvious internal feeding.