PESTS OF STORED FOODS
By: Stephen B. Bambara and Michael Waldvogel, Entomology Extension
Insect Note - ENT/rsc-27
Few pest problems can be more disturbing that to open a bag or box of baked goods and discover that it is infested with insects. There are a number of stored product pests that find their way into items stored on our kitchen or pantry shelves, and it is often difficult, if not impossible, to tell when the item becomes infested. Just because a box "looks" sealed does not mean that insects cannot find their way inside anytime before packaging, during storage in a warehouse, retail store or even in your home. Sometimes, pests show up in places other than a pantry. Regardless of where we find them, the key to solving the problem is to locate the source of the infestation. These insects will often attack any item made of plant material. Typical sources of a problem are items such as:
Insect pests that attack stored grains and stored products are usually beetles or moths. With the beetles, both the immatures (larvae) and the adults feed on stored products. In the case of the moths, only the larvae (caterpillars) feed on plant products; the adults either feed on nectar or they may not feed at all. We also categorized these pests by where they feed.
beetles - These small
(about 1/5 inch long) reddish-brown
beetles feed primarily on flour, meal and other flour-based items. Although
they have wings, flour beetles rarely fly.|
Signs of an infestation: larvae and/or adults on the infested material; adults crawling on nearby surfaces.
- The beetles
are smaller than flour beetles (about 1/8
inch) and brown in color. They are characterized by saw-like margins along
the area behind the head. Aside from very slight differences in their
appearance, the sawtooth grain beetle (shown at left) does not fly, whereas
the merchant grain beetle does. Of the two species, the sawtooth grain
beetle is more common.
and Drugstore Beetles
- These brownish
beetles (about 1/5
inch long) pests are usually found in spices (particularly red pepper),
bread, flour, meal, and similar cracked, processed or broken materials.
Dry pet foods frequently become infested with these insects. They sometimes
infest whole grains, but prefer those that have been broken open. They
will eat almost any dried plant material.
Indianmeal moth - This is the most common stored product pest found in North Carolina. The larvae (immatures) are pinkish-white in color with brownish head capsules. The larvae spin silk webbing over the surface of their food. The adults are small (3/8 inch wingspread) moths with coppery-colored wings. As the larvae finish their development, they often crawl from their food source and onto walls and ceilings.
Signs of an infestation: larvae or webbing on surface of infested material; larvae or pupae spun into crevices along walls, ceilings, or cupboards; adults flying about the room.
These insects feed inside whole grains.
- These beetles are about 1/4
inch long and dark brown in color and have a characteristic
long snout with chewing mouthparts at the tip. Like grain borers,
the female weevil chews a small hole in the grain surface and deposits
her egg. The larva tunnels into the grain and feeds on the kernel until
it completes its development and pupates inside the kernel. The adult
weevil chews its way out of the hollow grain.
grain moth - This
small (3/8 inch)
moth has buff-colored wings. The adult lays its eggs on the surface
of the grain. The larva chews its way into the grain and feeds on the
kernel before forming a pupal case. The moth pushes its way out.
Pest information and control recommendations presented here were developed for North Carolina and may not be appropriate for other states or regions. Any recommendations for the use of chemicals are included solely as a convenience to the reader and do not imply that insecticides are necessarily the sole or most appropriate method of control. Any mention of brand names or listing of commercial products or services in the publication does not imply endorsements by North Carolina Cooperative Extension nor discrimination against similar products or services. All recommendations for pesticide use were legal at the time of publication, but the status of pesticide registrations and use patterns are subject to change by actions of state and federal regulatory agencies. Individuals who use chemicals are responsible for using these products according to the regulations in their state and to the guidelines on the product label. Before applying any chemical, always obtain current information about its use and read the product label carefully. For assistance, contact the Cooperative Extension Center in your county.
Distributed in furtherance of the acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.