Pantry Pest Identification in Idaho

Oh, no. Pantry Pests!

This guide aims to help our fellow Idahoans identify common insect pests in pantries and kitchens. This guide is not meant to be all-inclusive but to cover the most common occurring species you may encounter. If you find a species you are unsure of, please get in touch with us for further help. Every pest infestation may differ due to circumstances. It is helpful to find both adult and juvenile insects. Using these specimens and other clues, such as the food source, may help you identify the pest and take appropriate action (see management chart). A magnification device like a hand lens may help identify insects.

PEST BIOLOGIES

Pantry Pest Identification in Idaho

ANT = Ant adults have distinct elbowed antennae. They often nest in and around the home. The adults frequently leave and return to the nesting site to gather food for the colony. Numerous species exist in the Pacific Northwest, but common species include the pavement, sugar, citronella, black garden, and Formica ant.

CLOTHES MOTH = Clothes Moth adults are small insects that commonly infest closets. Larvae (caterpillars) are cream-colored with a red head. They feed on various fabric materials—sometimes carrying around silken cases full of excrement and fibers. The most common species is the webbing clothes moth, but the casemaking clothes moth can also infest homes.

DERMISTID BEETLE = Dermestid Beetle adults are mobile, and many species can fly. Larvae (shown on the left) molt multiple times, leaving behind cast skins in their food source. Larvae are not as mobile but cause the most feeding damage. Once fully developed, larvae often seek wooden material to pupate in. Common species include carpet beetles, larder beetles, and hide beetles.

FLOUR BEETLE = Flour Beetle adults can live for about a year. They are quite mobile as they search for food or a mate. Larvae have limited mobility. They can go from egg to adult in six weeks in a warmer environment. Most adults do not fly, except for the confused flour beetle. Common species include the red and confused flour beetle.

FLOUR MOTH = Flour Moth adults are found in and around the pantry. The larvae (caterpillars) are in the damaging stage and feed on various foods. Larvae cannot chew through packaging, so the eggs are typically laid near a crack/crevice of certain foods in the pantry. Common species include the Indian meal moth and the Mediterranean flour moth.

COCKROACH = Cockroaches prefer areas that are moist, dark, and warm. They can move fast and tend to hide. They are mostly active at night. Nymphs and adults look and behave similarly, but in some species, adults have wings. Roaches can reproduce quickly. German, American, Oriental, and brown-banded cockroaches are common pest species.

WEEVIL = Weevils chew small holes into whole grains and then lay their eggs inside. Nearly sealed off inside the kernels, larvae are protected from most outside forces. Larvae feed from the inside, unable to move, until they pupate and then emerge as adults, leaving the kernel to mate and lay eggs. Common species include the granary and rice weevil.

ADULT IDENTIFICATION

Pantry Pest Identification in Idaho

Questions to ask when trying to determine the pest you’re looking at. Are the antennae at least 1/2 the length of the entire body? YES = COCKROACH

NO = Move on to the next example… Does it have a long snout like a droopy straw? YES = WEEVIL

NO = Move on to the next example… Does it have elbowed antennae? YES = ANT

NO = Move on to the next example… Is the body wedge-shaped, covered in small fuzzy hairs? YES = DERMISTID BEETLE

NO = Move on to the next example… Is it reddish brown, approximately 1/8″ long, and pill-shaped? YES = FLOUR BEETLE

NO = Move on to the next example… Is it mothlike in appearance? YES = Use the Common Diet section to determine potential moth species. NO = Preserve the specimen in a container with rubbing alcohol or in the freezer and seal the container. Contact our office for identification help.

JUVENILE IDENTIFICATION

Are the antennae visible and at least 1/2 length of the entire body? YES = COCKROACH

NO = Move on to the next example… Does it look wormlike but with lots of long fuzzy hairs on it? YES = DERMISTID BEETLE

NO = Move on to the next example… Is it wormlike, legless, and the body bends in a C shape? YES = WEEVIL

NO = Look for adult specimens and use the other available information to help you resolve what species it may be.

COMMON DIET

Pantry Pest Identification in Idaho

ANT = Sugar and common cooking spices, whole kernel grains (e.g., whole wheat, rice, corn kernels), ground or broken grains (e.g., flour, cornmeal, corn grits), other human food, dried dog food CLOTHES MOTH = Clothing PREFERRED (e.g., cotton, wool, or silk) DERMISTID BEETLE = Animal hides and skins PREFERRED (e.g., feathers, furs, leather, and taxidermy), Clothing (e.g., cotton, wool, or silk), whole kernel grains (e.g., whole wheat, rice, corn kernels), ground or broken grains (e.g., flour, cornmeal, corn grits) FLOUR BEETLE = Ground or broken grains PREFERRED (e.g., flour, cornmeal, corn grits), sugar and common cooking spices, whole kernel grains (e.g., whole wheat, rice, corn kernels), other human food, dried dog food FLOUR MOTH = Ground or broken grains PREFERRED (e.g., flour, cornmeal, corn grits), sugar and common cooking spices, whole kernel grains (e.g., whole wheat, rice, corn kernels), other human food, dried dog food COCKROACH = Sugar and common cooking spices, whole kernel grains (e.g., whole wheat, rice, corn kernels), ground or broken grains (e.g., flour, cornmeal, corn grits), other human food, dried dog food WEEVIL = Whole kernel grains PREFERRED (e.g., whole wheat, rice, corn kernels)

PEST MANAGEMENT

ANT = Check regularly for expired foods and discard foods past expiration. Store food or susceptible products in airtight containers to prevent infestations. Seal cracks and holes in walls or cupboards to create physical barriers in your house or pantry. Remove food crumbs and particles in cabinets, countertops, and floors. Use pesticides labeled for the pest. Boric acid is effective against roaches and ants. Use baits labeled for target pest. Keep baits out of reach of pets/children. Baits are effective for roaches. CLOTHES MOTH = Store food or susceptible products in airtight containers to prevent infestations. Seal cracks and holes in walls or cabinets to create physical barriers in your house or pantry. Use pesticides labeled for the pest. Boric acid is effective against roaches and ants. Use baits labeled for target pest. Keep baits out of reach of pets/children. Baits are effective for roaches. Use sticky traps for roaches or pheromone lure traps to monitor some moths or dermestids in the home. DERMISTID BEETLE = Check regularly for expired foods and discard foods past expiration. Store food or susceptible products in airtight containers to prevent infestations. Seal cracks and holes in walls or cupboards to create physical barriers in your house or pantry. Remove food crumbs and particles in cabinets, countertops, and floors. Use pesticides labeled for the pest. Boric acid is effective against roaches and ants. Use sticky traps for roaches or pheromone lure traps to monitor some moths or dermestids in the home. FLOUR BEETLE = Check regularly for expired foods and discard foods past expiration. Store food or susceptible products in airtight containers to prevent infestations. Remove food crumbs and particles in cabinets, countertops, and floors. FLOUR MOTH = Check regularly for expired foods and discard foods past expiration. Store food or susceptible products in airtight containers to prevent infestations. Remove food crumbs and particles in cupboards, countertops, and floors. COCKROACH = Check regularly for expired foods and discard foods past expiration. Store food or susceptible products in airtight containers to prevent infestations. Seal cracks and holes in walls or cupboards to create physical barriers in your house or pantry. Remove food crumbs and particles in cabinets, countertops, and floors. Use pesticides labeled for the pest. Boric acid is effective against roaches and ants. Use baits labeled for target pest. Keep baits out of reach of pets/children. Baits are effective for roaches. Use sticky traps for roaches or pheromone lure traps to monitor some moths or dermestids in the home. Limit moisture and humidity in pantry areas (e.g., sealing leaky pipes). WEEVIL = Check regularly for expired foods and discard foods past expiration. Store food or susceptible products in airtight containers to prevent infestations. Remove food crumbs and particles in cabinets, countertops, and floors.

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Adapted from PNW 729 | Published February 2020 | © 2020 by the University of Idaho

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