LABORATORY STUDIES OF A DEVICE TO DETECT INSECTS IN GRAIN, AND OF THE DISTRIBUTION OF ADULTS OF THE RUSTY GRAIN BEETLE, CRYPTOLESTES FERRUGINEUS (COLEOPTERA: CUCUJIDAE), IN WHEAT-FILLED CONTAINERS

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Abstract
Various models of a device for detecting insects in stored grain were effective for trapping adults of the rusty grain beetle, Cryptolestes ferrugineux (Stephens), in laboratory experiments in which the insect population was known. At 30 ± 1 °C and 65 ± 5% relative humidity the number of beetles trapped increased with the time the traps were immersed in the grain. The number of beetles caught was affected by population density, duration of trapping period, position and contour of the trapping surface, location of the trap, size and shape of the container, and chemotactic stimuli. The distribution of beetles in wheat-filled containers was influenced by the shape and size of the container, duration of the sampling period, and geotactic factors. More beetles were recovered from wheat nearest the floor of filled containers of 3.8-1. capacity than from higher levels. In similar containers held in darkness, as many beetles were found near the surface as near the floor up to 14 days, but at 21 days nearly 41% were found near the floor. Drums of 105-1. capacity kept in darkness contained approximately equal numbers of beetles in the top and bottom one-third portions of wheat. More beetles were found in traps baited with rotting grain than in unbaited traps. Males and females were found in equal numbers in baited traps, or near the floor of wheat-filled containers.