STUDIES ON THE BEHAVIOR OF THE HOUSEFLY, MUSCA DOMESTICA L.

II. SOME ENVIRONMENTAL FACTORS AFFECTING THE NIGHTTIME RESTING BEHAVIOR OF FLIES

Abstract

The diurnal behavior and activity patterns of the houseflies released in a small container were studied with special reference to nighttime resting habit under different lighting and temperature conditions, and various feeding-deprivation schedules.
It was shown that the lowest intensity of light had a considerable effect on houseflies: when flies were placed in continuous illumination after being kept in alternating 12 hr light: 12 hr darkness cycle, they showed the nocturnal resting behavior only once under relatively dim light (below 1000 lux) . Over this light intensity (about 2000 lux) the characteristic behavior no longer occurred.
This resting behavior was shown to be affected little by temperature in the range 24.5-35 C. Flies tended to exhibit some modified behavior patterns and unusual activity pattern at approximately 15 C. Under more extreme temperature conditions, e. g. lower than 10 C or higher than 40 C, they completely failed to show usual behavior and activity patterns.
It was demonstrated that the overall activity tended to increase markedly from starvation. Even in starved flies, however, a considerable decrease in activity could be detected at the onset of subjective night. Feeding also had marked depressant effect on the activity of hungry flies. From the behavioral point of view it was possible to distinguish this decreased state of activity into the following two categories: one is caused by some factors controlling circadian rhythms and causes the fly to rest on the ceiling; the other is concerned with food intake and behaviorally keeps the fly staying mainly on the floor for at least three hours. Hence flies had to be fed to repletion on sucrose solution a few hours before the onset of subjective night in order to keep the flies to rest stably on the ceiling during subjective night.