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Home , Confused flour beetle, Flour beetle, Indianmeal moth, Pest (organism)

PANTRY PESTS

Integrated 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, distance to pupate. are easy to overlook because the involved are quite small, especially in The Indianmeal is a fairly distinct the egg and larval stages. Often the small moth with reddish brown fore- first indication of the is the wings that have a coppery luster on (actual size) appearance of small flying about the outer two-thirds and are whitish or the presence of in or near the gray on the inner or body portion. The food package. female moth lays its eggs singly or in adult groups on food material. Eggs hatch IDENTIFICATION AND within a few days into small, whitish Figure 1. . LIFE CYCLES . The most common insects infesting food in the home are in the or- Larvae of the Indianmeal moth spin a (T. castaneum); and the drugstore ders (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 , from which the granary weevil (Sitophilus granarius), ther grublike and legless or have only adult moth later emerges. The Indian- and the 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 , 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 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 and foods: the warehouse beetle (actual size) cereal products, , cornmeal, rice, (Trogoderma variabile); the sawtoothed dried , dehydrated , 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 (Tribo- mature larvae can often be found in lium confusum) and the 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, chips, , dead , origin, especially grain and grain prod- and dead insects. ucts like , meals, breakfast foods, (actual stock and poultry feeds, , size) Adult beetles have oval bodies that are nutmeats, candies, and ; 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, seed, and (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. (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.

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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 Traps seeds, and 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. food substance. The small, yellowish in a refrigerator or freezer. Also, as a are chemicals (in this case white grubs are covered with long, general practice, storing infrequently a sex attractant) produced by an or- silky, yellowish brown hairs and are used food items (e.g., pancake flour, ganism to affect the behavior of other about 1⁄6 inch long when fully grown. grains, spices, etc.) in the freezer pre- members of the same species. The sex The pupae are within a closed cell vents infestations from developing. pheromone attracts adult male moths composed of small particles of the food into the trap where they get stuck on substance cemented together with a se- Pheromone traps are available in many the sticky sides; these traps will not cretion of the larvae. The period from retail stores to monitor and trap attract the female moths, but may re- egg to adult is about 6 weeks. Indianmeal moths. are not duce their ability to produce eggs if recommended. they catch males before they can mate. The drugstore beetle is a very general feeder, attacking a great variety of Detection Place the traps in the area of a previ- stored foods, seeds, pet foods, spices, If you find small moths or beetles ous infestation and check them and pastry mixes, and has been said to crawling or flying around your kit- weekly. Most traps remain effective “eat anything except cast iron.” It gets chen, look for the food source of these for about 3 months. Whenever you its name from its habit of feeding on pests and remove it immediately. If catch a new batch of moths in traps, it almost all drugs found in pharmacies. you locate the infestation before it is time to inspect packages again. In the home, however, the most com- spreads to other packages, control mon food materials infested by this may be relatively easy. The source is Prevention and Sanitation beetle are pet foods, drugs, and cereals. commonly a package damaged at the Most home infestations of pantry The drugstore beetle lays eggs in al- store or an opened one that is little pests maintain themselves on spills in most any dry, organic substance. After used or forgotten. The best thing to do the crevices of cupboards and drawers hatching, the small, white grubs tunnel with the package is seal it up and dis- or in opened packages of food stored through these substances and, when pose of it, removing it from the house for long periods of time. Following a fully grown, pupate in small cocoons. immediately. few general guidelines when storing The entire life cycle may take place in food products will help you avoid less than 2 months. Cleaning Up an Infestation many potential problems. Most commonly, by the time the in- • Do not put exposed food on shelves. DAMAGE sects are noticed they have already Place it in containers with tight- Pantry pests damage food by contami- spread to other food packages. Care- fitting lids (plastic bags are not nating it with their bodies and their by- fully inspect all packages, especially adequate). products. The larval stage of the those that have been opened or are ex- • Regularly clean shelves, bins, and Indianmeal moth produces frass (ex- posed. Destroy any that give the slight- all other locations where there is crement) and webbing, and some est indication of infestation. Other than any possibility of flour or other food beetle larvae produce secretions that the insects themselves, telltale signs in- particles accumulating. Certain give food a disagreeable odor and clude webbing in tight places of a pests need only small amounts of taste. Setae (hairs) from the warehouse package or tiny holes in the container. food to live and breed. Soap and beetle can irritate the mouth, throat, Insects are less likely to invade pack- water is great for cleaning flat areas, and stomach of people who eat in- ages that have their original seal, but and vacuuming with a crevice fested products. In addition, pantry more commonly infest those that have attachment will help clean cracks, pests might introduce microbes into been opened or that have been on the edges, and corners. the food that could produce mycotox- shelf for a long time. Before replacing • Do not mix old and new lots of ins (highly carcinogenic compounds), noninfested packages, wash shelves foodstuffs. If the old material is in- especially if the food is stored in warm, with soap and water, and scrub corners fested, the pest will quickly invade humid conditions. and crevices or vacuum them with a the new.

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• Clean old containers before filling • Pantry pests can also breed in rodent Olkowski, W., S. Daar and H. them with fresh food. They may be baits. Be sure to frequently check Olkowski. 1991. Common-Sense Pest contaminated and cause a new infes- and discard infested baits. Control. Newton, CT: The Taunton tation. Press, Inc. • Do not purchase broken or damaged COMPILED FROM packages of food materials. They are Koehler, C. S. et al. 1982. Common Pan- Strang, T. J. K. 1992. A review of pub- more likely to become infested. try Pests and Their Control. Oakland: lished temperatures for the control of • Construct storage units so that they Univ. Calif. Div. Agric. Sci. Leaflet pest insects in museums. Collection Fo- are tight and can be cleaned easily. 2711. rum 8:41-67. • Store bulk materials, such as pet foods, in containers with tight-fitting REFERENCES UC Statewide IPM Program. Dec 2000. lids. Mallis, A. 1997. Handbook of Pest Con- Pest Notes: Clothes Moths. Oakland: • Keep storage units dry. This is im- trol. 8th ed. Cleveland: Franzak and Univ. Calif. Agric. Nat. Res. Publ. 7435. portant because moisture favors the Foster Co. Also available online at http:// development of pantry pests; dry- www.ipm.ucdavis.edu/PMG/ ness discourages them. Marer, P. 1991. Residential, Industrial, PESTNOTES/pn7435.html • Some pantry insects breed in the and Institutional . Oakland: nests of and insects and may Univ. Calif. Agric. Nat. Res. Publ. 3334. migrate from these into homes. Eliminate any nests found in or near the home.

For more information contact the University of California Cooperative Extension or agri- cultural commissioner’s office in your coun- ty. See your phone book for addresses and phone numbers.

CONTRIBUTORS: M. K. Rust and V. R. Lewis EDITOR: B. Ohlendorf TECHNICAL EDITOR: M. L. Flint DESIGN AND PRODUCTION: M. Brush ILLUSTRATIONS: Fig. 1: Koehler, C. S. et al. 1982. Common Pantry Pests and Their Control. Oakland: Univ. Calif. Div. Agric. Sci. Leaflet 2711. Fig 2: Jacqueline Lamer Lockwood. Figs. 3–5: David Kidd.

Produced by IPM Education and Publica- tions, UC Statewide IPM Program, Universi- ty of California, Davis, CA 95616-8620

This Pest Note is available on the World Wide Web (http://www.ipm.ucdavis.edu)

This publication has been anonymously peer reviewed for technical accuracy by University of California scientists and other qualified profes- sionals. This review process was managed by the ANR Associate Editor for Pest Management. The University of California prohibits discrimination against or harassment of any person employed by or To simplify information, trade names of products seeking employment with the University on the basis of race, color, national origin, religion, sex, physical have been used. No endorsement of named products or mental disability, medical condition (cancer-related or genetic characteristics), ancestry, marital status, is intended, nor is criticism implied of similar products age, sexual orientation, citizenship, or status as a covered veteran (special disabled veteran, Vietnam-era that are not mentioned. veteran, or any other veteran who served on active duty during a war or in a campaign or expedition for which This material is partially based upon work a campaign badge has been authorized). University policy is intended to be consistent with the provisions supported by the Extension Service, U.S. Department of applicable State and Federal laws. Inquiries regarding the University’s nondiscrimination policies may be of Agriculture, under special project Section 3(d), directed to the Affirmative Action/Staff Personnel Services Director, University of California, Agriculture and Integrated Pest Management. Natural Resources, 300 Lakeside Dr., Oakland, CA 94612-3350; (510) 987-0096.

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