It can be distinguished chiefly by slight projections or knobs on each front corner of the pronotum, and its club-shaped antennae. Males and females are identical in appearance both as larvae and adults. The adult is usually reddish brown, or sometimes black. Distribution[ edit ] The foreign grain beetle is found in tropical and temperate regions.
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Antennae are slender except for the last three segments, which are distinctly enlarged. They are about the size of a sawtoothed grain beetle, to which they are closely related, but somewhat broader. They are easily distinguished by the single conspicuous toothlike lobes at the front corners of the prothorax. Adults are capable of flight.
Young larvae are white, and mature larvae are grayish with the last few segments darkened. They are similar in shape and size to larvae of the sawtoothed grain beetle and have no forked process at the tip of the abdomen. Foreign grain beetle. Larval development is completed in days. When ready to pupate, the larva constructs a chamber of food particles cemented together. It then attaches itself to the substrate with a brownish substance from the anal aperture.
Pupation occurs after a prepupal period of days, and adults emerge days later. Thus, the development cycle is about 30 days under favorable conditions. Females begin laying eggs days after emergence. Most oviposition bouts last days and alternate with periods during which no eggs are laid days. Daily oviposition rates are eggs but can be as high as eggs.
Peak oviposition occurs 15 days post emergence and days post emergence. Mated males and females have an average lifespan of and days, respectively. Unmated beetles live considerably longer — males days — females days. Humidity is very important to the survival of this beetle. Low humidities are unsuitable for both larval development and oviposition. Humidity has little effect on the egg, prepupal or pupal stages.
Most larvae have 4 instars, however, as humidity decreases, the proportion with 5 instars increase. It is a scavenger that feeds on molds, dead insects, and damaged foods. On cereal grains, the embryo is a suitable food material. However, when found in large numbers they are probably feeding on molds present in the food. Foreign grain beetles have been reared on pure cultures of certain molds commonly found in grains and are considered a good indicator of damp storage conditions.
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Tropischer Schimmelplattkäfer - Ahasverus advena