Grain Beetles: Pests of Grains Warehouse Beetles and Others

Warehouse Grain Beetle Other Beetles Pantry Pests Grain Beetles Scavenger Beetles Crop Beetles

Larder Beetle

The Larder Beetle is also known as a kitchen beetle. They are identified by their brownish-black body, white and black markings and a cream colored band across the top of their wings with three black dots on each wing band.
Larder beetles are grouped in the same family of insects as the skin beetle, the hide beetle and carpet beetles although they do not just feed on carpet. They will feed on any stored animal or plant products like leather, insects, birds, cured meats, cheese, tobacco and dried fish meal. Larder beetles will also feed on animal carcasses such as mice or squirrels that die in buildings.

Adult Larder Beetles will breed throughout the year, with females laying six to eight eggs. Larvae are worm like, are covered in dark brown hairs and have a pair of spines on their tail end that curve backwards. Larder beetle larvae prefer dark places and will migrate into wood, cork or insulation so they can pupate into adults. Once adults emerge, they mate and lay their eggs near a food source.

Home infestations can occur as a result of a cluster fly or face fly problem. These flies seek shelter in the summer and often die within the homes walls. The death of the flies can often attract larder beetles the following year.

Foreign Grain Beetle

Foreign Grain beetles are small reddish brown insects that are in the same family as a saw-toothed grain beetle.
They are similar in size, but the foreign grain beetle does not have the saw-toothed projections. They do however have two peg like projections located just behind their head and a clubbed antenna. These pantry pests are strong fliers and are often mistakes for fruit flies or gnats.

Foreign Grain Beetles are a frequent pest in new homes. They are not normally associated with grain or other stored products, but will eat grain that is old and moldy. This insect, also known as the “fungus beetle” feeds on molds and fungi that grow on wet plaster, wall board or poorly seasoned lumber. They are also attracted to sawdust that collects behind walls during construction.

Adult females lay their eggs on sawdust; after hatching, the larvae grow and feed on the fungi. During late summer, adults move out of the walls and are attracted to windows and lights. They are commonly found outdoors, but they will enter homes through screens, cracks and crevices or around windows and doors.

Rusty Grain Beetle and Flat Grain Beetle

The Rusty Grain Beetle and the Flat Grain Beetle are very similar insects, so similar in fact that most people just group them together instead of trying to distinguish them. They both have a flat reddish brown body and are 1 ½ inches long with an antenna that is roughly the same size as their body. Females deposit their eggs on grain and when hatched, the larvae feed on the germ layer of wheat. The larvae form a gelatin looking cocoon that food particles cling to and that conceals them until they pupate into adults.

The Rusty and Flat grain beetle are found in the northern United States and Canada and prefer high moisture grain or moist decaying food. They will not infest grain unless the grain has already been damaged. These grain beetles are fast reproducing insects and are the most common pest of farm stored wheat.

Warehouse Grain Beetle

The Warehouse Grain Beetle is identified by its 1/8 inch long oval body and its brown and yellow wings. Females lay around 90 eggs on infested food. Larvae are hairy and worm-like and after hatching feed on the infested food.
They feed on cereals, candy, cocoa, cookies, cornmeal, fish meal, pet foods, flour, nuts, dried peas, beans, pasta, potato chips, spices, dead animals and dead insects. Ingesting infested food that contains the molted skins of the larvae can cause intestinal irritation.
The warehouse grain beetle is common in warehouses storing food, hence its name. They are found all over the United States, usually around seaports.

Credits:
Our thanks to Lani Powell for research and writing which made this grain beetle information page possible.