Sawtooth Grain Beetle

The sawtooth grain beetle is a small insect. The adult is slightly less than 1/8″ long. Despite its small size, the sawtooth grain beetle is an important pest of stored food. It is common in homes, groceries, processing facilities, and warehouses.

When the adult beetle is viewed from above, tiny serrations are visible on each side in the area behind the head. These “teeth” give the sawtooth grain beetle its common name. The scientific name is Oryzaephilus surinamensis (L.). The adult beetle's body is slender and brown.

Another beetle, the merchant grain beetle, is often confused with the sawtooth grain beetle. The most obvious difference is that the sawtooth grain beetle does not fly. The merchant grain beetle does fly.

The sawtooth grain beetle commonly attacks stored grain. It cannot break whole kernels, but it readily enters kernels that are cracked or broken. The adult beetle deposits eggs in crevices in the food. When the eggs hatch, the larvae feed and grow. After it has developed, the larvae make small cases where they change into adult beetles.

Besides grain, sawtooth grain beetles attack many food products. Because the adults are very small, they can squeeze into packages that appear to be sealed. They will readily infest cereal, flour, candy, pet food, and pasta.

The first step in controlling sawtooth grain beetles is a thorough inspection. It is important to find everything that the larvae are eating. Check every package in the pantry and cabinets. Check the area where pet food or animal feed are stored. Separate everything that is infested. Most experts recommend discarding all infested food items.

If infested items must be saved, they can be heated or frozen to kill the insects. Heating to 125° for an hour will kill all stages of the beetle. Freezing to 0-5° for 24 hours will also kill the insects.

While the pantry is empty, vacuum the shelves thoroughly. This will remove any insects that are hiding. It will also remove tiny food particles that may have fallen into the crevices. Take the vacuum bag outside to empty it.

It is sometimes necessary to apply insecticide to get complete control. Aerosols can be effective in cracks and crevices. If the infestation is very heavy, a contact insecticide may be needed to eliminate the active adult beetles. A pest control professional can advise if insecticide treatment is necessary. He or she will have the products and equipment needed to make these treatments.