Studies on the Behavior of the Housefly, Musca Domestical. I. The Behavior and Activity Patterns Under Experimental Conditions With Special Reference to the Nighttime Resting Habit

The behavior and flight activity patterns of the houseflies released in a small container were studied under various light regimes. Under the conditions of continuous illumination the activity of the flies stayed on a moderate level, the flies gathering mostly on the light surfaces of the container. Upon switching off the illumination they exhibited a characteristic upward movement and rested quietly on the ceiling. When the flies were placed in continuous illumination after they had been entrained in alternating 12 hr light: 12 hr darkness cycle for three days, they showed a significant change in the behavior with the time; they displayed a period (about 5 hr) of high activity several hours after the onset of light, and then in spite of continuous illumination the majority of the flies rested quiescently on the ceiling about 12 hr after the onset of light. This fact suggested that the characteristic nighttime resting behavior might be coupled with some internal factor which controls circadian rhythms (rhythms of approximately a 24 hr cycle) of activity in the fly. This resting behavior, however, occurred only once under continuous illumination because it tended to eliminate circadian rhythms.