The saw-toothed grain beetle and the
merchant grain beetle are slender, flat, brown beetles that
are about 1/10 inch long.
Both beetles are similar in appearance, with
six saw-like tooth projections on each side of the thorax (section between head and abdomen).
The saw tooth beetle is found in warmer climates and does not fly. The merchant grain beetle flies.
The saw-toothed grain beetle has smaller
eyes than the merchant grain beetle an
a much larger area just behind the eyes.
In
both larval and adult stages, these beetles feed on all food of plant origin, especially grain and grain products like flours, meals, cereals,
dried meats,
breakfast foods, stock and poultry feeds, coconut, nut meats, candies, and dried fruit; it is not uncommon to find these beetles infesting
pet food, bird seed, and rodent bait.
They are small enough to very easily penetrate tiny cracks and crevices in packages food products.
The biology of both beetles is nearly identical and they are managed in the same
manner so that it is not necessary to distinguish the two species.
The adult beetles live an average of 6 to 10 months,
but some individuals may live as long as 3 years.
The female beetle of both species drops her eggs loosely among the foodstuffs or
tucks them away in a crevice in a kernel of grain.
Eggs are laid either singly or in small masses in crevices in the food supply, or may be laid freely in items such as flour or cereal.
When the small, slender, white eggs hatch, the emerging larvae crawl and feed on the food stuff.
The larva nibble on finely divided food particles, it cannot feed on large particles such as whole grains.
They become full grown in about 2 weeks during summer weather and then construct delicate cocoon-like coverings by
joining together small grains or fragments of foodstuffs with a sticky secretion.
Within this cell, the larva changes to the pupal stage.
Development from egg to adult may take from 3 to 4weeks in summer.