A Peculiar Phenomenon Observed in Larval Populations of the Flour Beetle Tribolium confusum Duv

Abstract

I HAVE observed that if small masses of coarsely sifted whole-wheat flour (64 gm. in a 150 c.c. beaker) are seeded with more than 800 eggs of the flour beetle Tribolium confusum Duv., and maintained at a suitable temperature and relative humidity (27° C., and 75 per cent r.h.), a peculiar distortion of the originally flat, level, upper surface of the flour mass occurs. There is a slight initial bulging upward commencing on the sixth day when the eggs hatch, no doubt due to the loosening of the flour by larval movement. This bulging increases up to about the twenty-first day, as shown in Fig. 1. There then takes placo a more or less rapid moulding of the surface into the rather graceful form seen at the bottom of Fig. 1, and in Fig. 2, which is a photograph of a median vertical section of a culture on the twenty-eighth day.