Adult emergence patterns in Musca autumnalis (Diptera: Muscidae).

Adult emergence patterns were investigated in four lines of face flies, Musca autumnalis De Geer, in a 16:8 (L:D) h photoperiod and corresponding 30:25 degrees C thermo-period. Most emergence occurred in a specific time interval ("emergence gate") that began at 2000 hours and continued until 1200 hours. A cohort of puparia completed emergence in two or three consecutive emergence gates. The four lines showed different median times and rates of emergence. Laboratory rearing seemed to select progeny of earlier median times and faster rates of emergence. F1 progeny of the two lines showed patterns of emergence intermediate between those of the parents. Female flies tended to eclose earlier than males in all lines.