Diurnal Activity of Three Insect Pests of Stored Products

Abstract

I WAS recently enabled, through the kindness of the mill staff, to carry out a series of observations over a 24-hour period in a certain flour mill. The mill contained bags of infested spaghetti which had been stacked up in preparation for fumigation. The stacking was done three days before the observations were made, and it was assumed that any disturbing effect of moving the bags during stacking had died down. The animals dealt with were Ephestia kühniella Zell. larvæ, Ptinus tectus Boie. adults and Calandra granaria L. adults. The observations consisted of hourly counts of the numbers of animals active on the surface of a certain area of the spaghetti bags. An electric torch was used for observing the animals, and it was allowed to play on them for as short a time as possible, so as to minimize its disturbing effect. During the mill's working hours, 8 a.m.–5 p.m., electric lighting was on, which together with daylight coming in from open doors gave dim light. Some machinery was in action, causing a certain amount of vibration. Readings of temperature and relative humidity were made directly after each count. The temperature only varied from 11.5 to 12.5° C., while the humidity was between 70 and 80 per cent throughout.