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House and Garden Series
F@stSheet Ent-1020
Stored product pests are found in
almost every home at some time. Yet few people recognize why stored product pests occur,
or how to identify them. Many are transported into the home from a store or warehouse.
Others originate in the home when susceptible items are stored for long periods of time.
Finding the same insect repeatedly in the home
is a good indication of a stored product pest problem. Pantry pests are generally more
common in kitchen or food storage areas, whereas fabric pests are found more frequently in
closets or in rooms with a source of natural fiber, leather, or fur. Location can be
deceiving, however. For example, some pantry pests infest carcasses of animals such as
mice, rats or birds that may have died somewhere in the structure--not just in the pantry.
Fabric pests may be found almost anywhere in a home.
Recognizing the pest will help you narrow down
likely sources of the infestation. This handout is designed to help you identify some of
the more common stored product pests.
MOTHS
Moths can be either pantry or fabric
pests. However color patterns, size and behavior can generally help determine the food
preference of the moth problem. Indian meal moth
is one of the most common indoor pests submitted to county Extension offices. This insect
is readily identified by its two-toned (tan and copper colored) wing pattern. This insect
feeds on dried fruits, nuts, chocolate, powdered milk, bird seed, dog food, and a variety
of grain products. Full-grown larvae are pale and cream-colored and are usually about 13
mm long (range 9-19 mm). When fully developed, Indian meal moth larvae frequently wander
in search of a place to pupate, and may be found on ceilings, walls and counter tops.
Although adult Indian meal moths are primarily nocturnal, they are occasionally seen
flying about during the day.
Control.
Like other food-infesting moths, the Indian meal moth must be controlled by first locating
and eliminating infested food products. Insecticide sprays are not always needed. Often
removing an old infested bag of flour is all that is needed. For heavier infestations,
pesticides can be applied to corners and cracks around food storage areas. Pyrethrin-based
foggers can provide temporary suppression of adult moths; but aerosols alone will not
provide control until all infested foods are discarded. Pyrethrin, resmethrin, allethrin,
and tetramethrin are common pesticides found in sprays designed for cockroach control.
They are relatively safe to use in the kitchen, and can be used to treat cracks and
crevices in food storage closets. If you have a pest control company that regularly
services your home, ask about pheromone traps that are designed to monitor and help reduce
pantry moth pests.
CLOTHES MOTHS
Clothes moths can be distinguished from Indian
meal moths and other food-infesting moths by their small size, wing shape and secretive
nature. Adult clothes moths
have a wingspan of about 1/2-inch and a body covered with shiny golden scales. Under a
hand lens, the head can be seen covered with a fluffy pompadour of reddish-golden hairs.
Adult clothes moths are not commonly seen because they tend to avoid light and are active
primarily at night. Clothes moth larvae feed primarily on protein-based fibers such as
woolen cloths and carpets, furs, pet hair, piano felts and natural hair brushes.
Control. Dry cleaning kills all stages of clothes moths, but will not prevent
re-infestaion. For this reason, recently dry-cleaned items should be placed in
cold-storage (furs), or sealed in air-tight containers protected with fresh cedar chips or
other fumigants. In general, cedar wood does not provide effective protection from clothes
moths unless the wood is freshly cut or chipped and the container well-sealed. Aromatic
oils found in cedar heartwood do kill clothes moth larvae if present in sufficient
concentration; however few cedar chests more than two or three years old produce
sufficient vapors to kill pests. Naphthalene and paradichlorobenzene (PBD) products more
effective, but must be sealed tightly with the clothes. Use 1-2 pounds of repellent per
100 cubic feet of air to kill moth larvae. Care must be taken with PDB crystals around
certain plastic products, as many types of plastics will soften or melt in the presence of
PDB fumes.
Infested articles may be sealed and placed in
chest-type freezers (-4° F or -20° C) for at least 7 days to kill eggs and larvae. It is
best to place infested articles in polyethylene bags prior to freezing to reduce the risk
of damage due to rapid changes in moisture content. Heat can also be used to disinfest
clothing articles. Clothes moths are killed by exposure to 122° F (50° C) for 11-14
minutes, or 140° F (60° C) for as little as one minute. Beware of possible heat damage
to some woolen articles at these temperatures. Regular (once or twice a month) airing and
beating of woolen rugs and clothing also is a very effective method of control. Beating
and brushing crushes eggs and larvae of clothes moths, and exposure to the hot sun causes
larvae to become irritated and drop from the fabric.
BEETLES
Numerous kinds of beetles can be found
feeding on stored food and pantry items. They include weevils, cigarette and drugstore beetles,
saw-toothed grain beetles, larder beetles, mealworms, and
various flour beetles. These beetles feed on a wide variety of stored grains, fruits,
spices, powdered milks, dried meats, or dead insects, birds, or mammals.
Some very small scavenger beetles, known as
minute fungus beetles and foreign
grain beetles, are periodically found in large numbers. This occurs most often in new
homes, where they appear to feed on fungi and mildew growing on wood and plaster drywall.
Control.
Controls for beetles are similar to those for pantry-infesting moths. First
locate the infestation source (or sources) then seal all un-infested foods in air-tight
containers such as screw-top glass, heavy plastic or metal containers.
Locating beetle infestations is often
difficult. Inspect all cracks and crevices where food debris may accumulate, check food
containers (many times even sealed containers may be infested inside and be loose enough
to allow insects to escape), check under and around cabinet voids and appliances for
spillage of grains, pet foods or other food products, vacuum and clean cabinets and doors
in infested areas thoroughly. Rodent nests are sometimes the source of a persistent beetle
infestation. Mice often hoard seeds and other stored products, which later become
infested. Until you locate the source of the problem, the infestation will likely continue
until the food source is consumed. If you have a pest control company that regularly
services your home, ask about pheromone traps that are designed to monitor and help reduce
pantry beetle pests.
After the source of infestation is eliminated,
seal all food products that might become infested in tight containers. Ordinary metal
kitchen canisters are not tight enough to exclude some insects. Tupperware containers, if
air-tight, may work.
With heavy or widespread infestations, you may
need to apply an insecticide spray to empty cupboards, drawers, and pantries. All food
products, utensils and containers should be removed from the treatment area before
spraying. Sprays must be allowed to dry before placing clean shelf paper on the shelves
and returning food items.
Prevention. Pantry pest problems can usually be avoided by using all dried food
within 2-4 months of purchase. Spices and other products that are to be kept for longer
periods should be sealed in airtight containers. When you buy packaged foods, check that
the bags or containers are well sealed. Keep food storage areas clean and clear of crumbs
or food particles. Pet food is a major source of stored product pests. Be sure to store
pet foods in well-sealed buckets or storage containers.
CARPET BEETLES
Carpet beetles are the most important beetle pests of fabric. Adult carpet beetles are small and round, approximately 1/16 to 1/8 inch-long. The wing covers are
either black or mottled, with various patterns of black, gray, yellow and red scales. The larvae are carrot-shaped
and are usually covered with numerous tiny, backward-pointing hairs. They feed on any
source of animal protein including dead mice or birds, dead insects, fabrics and carpet
made of natural fibers, dried meat, stuffed trophies, etc.
Control.
Many of the same methods used to prevent and control damage caused by clothes
moths can be applied to carpet beetles. In addition to inspecting furs, woolens, feathers,
silks, wool carpets and other such materials, look for infestations in accumulations of
dust and pet hair along baseboards, old bird or rodent nests in attics, and wherever dead
insects accumulate, such as window sills and light fixtures.
Sanitation is the key to preventing carpet
beetle problems. Woolen rugs, windowsills and light fixtures should be vacuumed
frequently. Woolen garments should be inspected and periodically washed or dry cleaned.
Pesticide treatment of woolen carpets (or natural hair pads sometimes used as cushioning
under carpeting), furniture with hair stuffing, and other infested sites, may be needed in
severe cases. Aerosol foggers do not work well unless all infested materials are first
located and destroyed or treated.
Infested fabric articles may be treated with
heat or cold, as described for clothes moths.
FOR MORE INFORMATION
For more information about cigarette and drugstore beetles, see Internet FastSheet Ent-1013. Images courtesy Gustafson Seed Company and Vopak, Inc.
Author:
Michael Merchant, Ph.D., Urban Entomologist, Texas AgriLife Extension Service
Publication information:
This publication is part of the House & Landscape Pest Series produced by the Department of Entomology, Texas A&M University, College Station, TX 77843-2475. The most recent update can be found at: http://dallas.tamu.edu/insects/Ent-1020.html. Series Editor: M. Merchant. For more information about arthropods, check out the Texas A&M Entomology Website at http://insects.tamu.edu
Last Revised: 9/6/01
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