Pantry Pests

PANTRY PESTS Integrated Pest Management in the Home Stored-product pests are usually parts of the house far from the original brought into the home in an infested food source because they move quite a package of food. Initially, infestations distance to pupate. are easy to overlook because the insects involved are quite small, especially in The Indianmeal moth is a fairly distinct the egg and larval stages. Often the small moth with reddish brown fore- first indication of the infestation is the wings that have a coppery luster on (actual size) appearance of small moths flying about the outer two-thirds and are whitish or the presence of beetles in or near the gray on the inner or body portion. The food package. female moth lays its eggs singly or in adult larva groups on food material. Eggs hatch IDENTIFICATION AND within a few days into small, whitish Figure 1. Indianmeal moth. LIFE CYCLES caterpillars. The most common insects infesting food in the home are in the insect or- Larvae of the Indianmeal moth spin a (T. castaneum); and the drugstore beetle ders Lepidoptera (moths) or Coleop- web as they grow and leave behind (Stegobium paniceum) and the cigarette tera (beetles). Adult moths and adult silken threads wherever they crawl. beetle (Lasioderma serricorne). Other beetles are easy to distinguish from When fully grown, the larva is about beetles that feed primarily on seeds or each other, but their larvae are a little 1⁄2 inch long and white with a greenish whole grains include the lesser grain more difficult to identify (see Figs. 1 or pinkish hue. This larva spins a borer (Rhyzopertha dominica), the bean and 4). Use a hand lens to examine the silken cocoon and transforms into a weevil (Acanthoscelides obtectus), the legs of the larvae. Beetle larvae are ei- light brown pupa, from which the granary weevil (Sitophilus granarius), ther grublike and legless or have only adult moth later emerges. The Indian- and the rice weevil (S. oryzae). These three pairs of legs, all located close to meal moth takes about 6 to 8 weeks to seed beetles are not covered in detail the head. Moth larvae have three pairs complete egg, larval, and pupal stages here, but their management is similiar of true legs, plus additional leglike during warm weather. to the other pantry beetles. structures further down the abdomen. Both larvae and adults of beetles feed Don’t confuse Indianmeal moths with Warehouse Beetle. The warehouse on foodstuffs, whereas only the larval clothes moths, which are smaller and beetle feeds on a wide variety of foods stage of moths consumes stored have more hair than pantry moths. For including cereals, candy, cocoa, cook- products. more information see Pest Notes: ies, cornmeal, fish meal, pet foods, Clothes Moths, listed in References. Meal Moths Indianmeal Moth. The most common Pantry Beetles species of meal moths found in the While there is only one major species home pantry is the Indianmeal moth, of moth that feeds on food products in Plodia interpunctella. All damage is the home, several species of beetles done by the larvae, which attack a wide commonly attack a wide variety of range of products, including cereal and foods: the warehouse beetle (actual size) cereal products, flour, cornmeal, rice, (Trogoderma variabile); the sawtoothed dried fruit, dehydrated vegetables, grain beetle (Oryzaephilus surinamenis) nuts, chocolate, candies, and other con- and the merchant grain beetle (O. mer- fections. When infestations are heavy, cator); the confused flour beetle (Tribo- mature larvae can often be found in lium confusum) and the red flour beetle Figure 2. Warehouse beetle. PEST NOTES Publication 7452 University of California Agriculture and Natural Resources Revised September 2002 September 2002 Pantry Pests flour, nuts, dried peas and beans, pas- these beetles feed on all food of plant tas, potato chips, spices, dead animals, origin, especially grain and grain prod- and dead insects. ucts like flours, meals, breakfast foods, (actual stock and poultry feeds, coconut, size) Adult beetles have oval bodies that are nutmeats, candies, and dried fruit; it is (actual size) about 1⁄8 inch long with a brown and not uncommon to find these beetles in- yellowish pattern on the wing covers festing pet food, bird seed, and rodent (Fig. 2). Female beetles lay up to 90 bait. larva eggs within the infested food. Larvae emerge and feed on the food. Larvae The biology of both beetles is nearly Figure 4. Confused flour beetle (left) are about 1⁄4 inch when fully grown identical, and they are managed in the and red flour beetle. and have numerous stiff setae, or hairs, same manner so that it is not necessary that emerge from dark-colored plates to distinguish the two species. The on the last few segments of their abdo- adult beetles live an average of 6 to 10 men, as well as a tail of long thin hairs months, but some individuals may live The eggs, which are coated with a that extends from the tip of the abdo- as long as 3 years. The female beetle of sticky secretion, become covered with men. They are very active and seek out both species drops her eggs loosely flour or meal and readily adhere to the new food sources to infest. In warm among the foodstuffs or tucks them sides of sacks, boxes, and other con- temperatures, the entire life cycle from away in a crevice in a kernel of grain. tainers. They hatch into small worm- egg to adult can be completed in 45 When the small, slender, white eggs like larvae that are slender, cylindrical, days. hatch, the emerging larvae crawl about and wiry in appearance. When fully actively, feeding here and there. They grown, the larva is 3⁄16 inch long and The setae of this beetle are shed within become fully grown in about 2 weeks white, tinged with yellow. At this the infested food product and can be during summer weather and then con- stage, it transforms into a small pupa. irritating to the mouth, esophagus, and struct delicate cocoonlike coverings by At first white, the pupa gradually digestive tract if they are ingested; con- joining together small grains or frag- changes to yellow and then brown, and sequently any food found infested with ments of foodstuff with a sticky secre- shortly afterward transforms into a this beetle should be discarded. tion. Within this cell, the larva changes beetle. In summer, the period from egg to the pupal stage. Development from to adult averages about 6 weeks. Sawtoothed Grain Beetle and Mer- egg to adult may take from 3 to 4 chant Grain Beetle. The sawtoothed weeks in summer. Cigarette Beetle and Drugstore Beetle. grain beetle and the merchant grain The cigarette beetle and the drugstore beetle are slender, flat, brown beetles Confused Flour Beetle and Red Flour beetle closely resemble one another, that are about 1⁄10 inch long. Both Beetle. The confused flour beetle and but the cigarette beetle is more com- beetles have six sawlike tooth projec- the red flour beetle are very similar in mon. Both beetles are about 1⁄8 inch tions on each side of the thorax (section appearance and can be most easily dis- long, cylindrical, and uniformly light between head and abdomen). The tinguished by examining the antennae: brown. The easiest way to distinguish sawtoothed grain beetle has smaller the antennae of the red flour beetle end the two is by the wing covers: the wing eyes than the merchant grain beetle abruptly in a three-segmented club, covers of the drugstore beetle have lon- and a larger area just behind the eyes while the confused flour beetle’s anten- gitudinal grooves, while those of the (Fig. 3). In both larval and adult stages, nae gradually enlarge towards the tip, cigarette beetle are smooth (Fig. 5). ending in a four-segmented club (Fig. 4). Adult beetles of these two species have shiny, reddish brown bodies that are about 1⁄7 inch long, flattened, and oval. These beetles have a very wide food range including cereals, damaged grains, grain products, shelled nuts, dried fruit, chocolate, drugs, and her- (actual (actual size) barium and museum specimens. size) The biologies of these two species are very similar; their average lifespan is about 1 year, but some have been known to live almost 4 years. The fe- Figure 3. Sawtoothed grain beetle (left) males lay their small, white eggs Figure 5. Cigarette beetle (left) and and merchant grain beetle. loosely in flour or other food material. drugstore beetle. ◆ 2 ◆ September 2002 Pantry Pests The cigarette beetle feeds on cured to- MANAGEMENT crevice attachment to remove eggs bacco, cigarettes, and cigars. It also Getting rid of food-infesting moths or and pupae. feeds on dried herbs, spices, nuts, cere- beetles takes continuous, persistent ef- als and cereal products, dried fruit, fort if the infestation has been present Pheromone Traps seeds, and animal products such as for a while. Some pests are capable of Of the major pantry pests, pheromone dried fish and meats, hair, and wool. In living for many weeks without food, traps are only readily available in the home this beetle is most commonly thus the threat of reinfestation exists retail stores for the Indianmeal moth. found in pet foods, cereals, nuts, and until they die off or are killed. Follow Pheromone traps for the Indianmeal candy. It may also infest dried pepper the guidelines for removing and clean- moth will not attract beetles. arrangements, wreaths, and spices ing up an infestation. It is best, at least such as chili powder or paprika. for several months after eliminating Use pheromone traps after the source the infested products, to store any sus- of the infestation has been removed to The cigarette beetle lays its eggs in the ceptible food in airtight containers or detect moths that remain in the house.

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