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The sawtoothed grain beetle, Oryzaephilus surinamensis, is a slender, dark brown beetle 2.4–3 mm in size, with characteristic "teeth" running down the side of the prothorax. The sawtoothed grain beetle is a secondary pest, in the UK, that attacks damaged grain. Carolus Linnaeus, the Swedish naturalist who defined taxonomic arrangements for the animal, plant, and mineral kingdoms acquired samples of the sawtoothed grain beetle from Suriname (Dutch Guiana) and named the species "Oryzaephilus surinamensis" because of this. (It is Latin for "rice-lover from Surinam".)
A relative of the sawtoothed grain beetle of the same genus, the merchant grain beetle, is more likely to be found in domestic dwellings since it requires higher more stable temperatures and can be found infesting biscuits and fruit and nut products. The adults can fly but rarely do. They can be differentiated by looking at the distance of the eye to the prothorax: with the merchant grain beetle it is less than half the vertical diameter of the eye.
The sawtoothed grain beetle lays its eggs loosely on foodstuffs at the rate of 6–10 per day, with total being 370 per female. The larvae are to be found within the mass of the foodstuff in the top centimetre or two. As mentioned above damaged cereal is entered through broken kernels, and the larvae feed on the germ, causing damage by reducing the percentage of grains which will germinate.
The total life cycle is 20–80 days at 18–37 °C (64–99 °F).
The sawtoothed grain beetle can survive in unheated warehouses in the UK, and is considered the most important pest of home grown grain in the UK. The beetles survive the winter hiding in cracks and infest new stocks of grain the following year. Both insects are distributed throughout the world and regularly imported into the UK in unprocessed cereals, oil cakes, and from grains from other stores.
Treatment in bulk storage situations normally is carried out by fumigation, and in domestic situations finding the infested material, disposing of it and carrying out a residual spray to kill off stragglers.
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