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Common Stored Product Pests
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Common Stored Product Pests

1) Case-bearing moth & larva
2) Drugstore beetle
3) Clothes moth
4) Sawtoothed grain beetle
5) Silverfish
6) Confused flour beetle
7) Rice weevil                                    
8) Spider beetle
9) Yellow meal worm
10) Fur beetle
11) Indian meal moth
12) Varied carpet beetle
13) house cricket
14) Furniture beetle
15) Larder beetle
16) Lesser grain borer
17) Maize weevil

The following treatment recommendations apply to each and every pest listed above.  Where there are any additional specifications, they are noted in the specific descriptions below.

Treatment Recommendations

All stored items should be searched for signs of infestation.  Remembering that not only opened products are vulnerable, but also products that are not yet opened.  Normally, this is what you do.  Look in your kitchen pantry/cabinets, or wherever you store food products.  Stand at the sink, take out all these stored products, (cake mixes, spices, cookies, crackers) one by one, shake a little out in your hand and check the inside of the box, methodically search through all the opened products first.  

After all the opened products are inspected, you must then go through and CHECK CLOSELY all of those that aren't opened as yet.  Closely inspect the packaging for any signs of insect infestation, open any packages that seem suspicious.  Infected products must be then discarded or heat treated.  Heat treatment means that all of the product must be maintained at 125 degrees Fahrenheit for a period of at least 45 minutes.  In residential setting, for human consumption, the infested products are better discarded. Infested animal feed can often be successfully heat treated before its intended use. Naturally, if you know where you purchased the infested products, you can return them for a refund.

In every cabinet where you have found evidence of the insects, clear out the cabinets entirely, use a strong vacuum to clean out the cabinets, paying special attention to the cracks and crevices where the insects hide.  Make sure you get up UNDERNEATH the shelves, both larva and adults will hide in and under the little nooks and crannies.   The thorough vacuuming is important, and can make or break the job.  If you do a good job, you won't even need to use any insecticides whatsoever.

As far as spraying the cabinets when you're done, DON'T do it with Raid - or any kind of insecticide that comes in a pressurized spray can - you'll get everything all greasy.  A good job of vacuuming is probably all you'll need.  Also don't use bleach or ammonia or pine oil, please don't use anything except the vacuum.

If you do use an insecticide, you must use one with a residual - none of the pressurized cans of insecticide have enough residual to do the trick.  No boric acid, bay leaves or mint leaves either.  Residuals are usually best applied by professionals, and especially where food products are stored.  An exterminator will have the knowledge and training to do this the proper way, using the proper chemical control.  The proper concentrate must be mixed (properly) with water and applied (properly) to specific areas, depending on the target insect.  If you DO use a professional, be sure to save a sample insect for him to examine and identify.  Be sure and check your choice of an exterminator with the BBB. But before you do anything rash, however, try doing it yourself, this way, and most of the time you won't need chemicals or the exterminator.

These pests come in your food products, right from the factory, if it's been processed, but they can also come from seeds, herbs or other natural products we have or store in our homes.  All processed foods have this problem, no matter how careful any manufacturer is.  It is impossible to eliminate a certain amount of "insect fragments" in these foodstuffs, so if you keep them too long, under the right conditions, you have bugs!  And even if you just bought it, the supplier probably had them too long, or even the manufacturer.  At some point, you will most probably meet up with one (or more) of the ones pictured at the top of this page.

Insect Descriptions

I won't get into any scientific names or anything, most people aren't interested in that information.  And these are only some of the stored product pests you can have.  There are many others, some quite exotic, especially if you bring food products in from other places.  Items that fit into this category also include decorative items that might not appear to be of food, plant or animal origin.

Case-bearing moth
So named because the larvae carry their pupal cases about as they feed and travel, case-bearing moths are much less likely to be found in your home than the Common Clothes moth.

Look for the faint, dark smudges on the wings of the adult.  The wings have a very slight, darker, dusky appearance, compared with the clothes moth, giving it a slightly dull appearance.  The eggs are visible only under a low-power microscope.  The larva of the Case-Bearing moth is much more easily identified because of their cases, open on one end, and dragged about, wherever they go.  The larvae only expose the first few segments, staying within their case for protection.

The larvae never leave their cases, and when ready to pupate, will seal off both ends of the case, and when the adult finally emerges, they cut through the end of the thin silken case.  The Case-bearing moth is usually found around carpets and heavy woolen draperies.  Case-bearing clothes moths are not that economically important, certainly not as much as the common clothes moth.

Drugstore beetle
The adults, the ones you will usually see, are small, about an eighth of an inch long, light brown or even red in color and have a "humpback" appearance.  They look almost identical to the

Cigarette beetle.  The wing covers of the Drugstore beetle have distinct grooves running from front to back.  Cigarette beetles have smooth wing covers.  Larvae of Drugstore beetles are hairless, the Cigarette beetle larvae look like they have a fuzzy coat

Drugstore beetles feed on all kinds of foods and spices, including leather and furs, hair, drugs and books.  Depending on conditions, they can have as many as four generations per year.  Normally, however, they have one generation per year in residential situations, so they are rather long-lived.

The females lay their eggs in singles, in the product they are infesting.  The larval stage can last as long as five months, followed by a relatively short period of less than three weeks in the pupal stage.  

Infested food products should be discarded, other materials, such as books and manuscripts can be fumigated.

common clothes moth
First of all, the adult stage (the moth) does no damage to fabrics or any other materials.  In fact, during it's adult stage, it eats or consumes no food, living on what it consumes during the larval stage.  It is this larval stage that this insect causes any damage by feeding on natural materials, wrapping itself in an open and chaotic web-mat of silk.  Larvae are not
normally visible or obvious in their day to day activities.  The silk is produced by a gland just under the head from a special spinneret.  Larvae may reach a size of almost a half inch and incorporate their rather large fecal pellets into their web-like mass.  The fecal pellets are often mistaken for "eggs."

Adult females lay their eggs, all within a couple of days, fertilized or not, on substances that will support the larval stages.  Unfertilized eggs, of course, do not hatch, but fertilized eggs will hatch, in a matter of days, depending on the temperature, and the larva will then crawl away and hide.  Larvae molt some four times before they construct a cocoon to pupate.  Cast-off pupal skins can often be seen protruding from cocoons.

The Common Clothes moth, in the larval stage, is the most important pest of Man's natural materials, far more than the Case-bearing moth, which looks quite like the Clothes moth.  And yes, these pests can go from life cycle to life cycle, right in your house, in your closet or attic.

To minimize the chance of either of these pests, have your natural material (wool, linens, etc.) dry cleaned after each use.  DON'T put them away "dirty."  Clothes moths prefer to dine on materials with traces of body oils, perspiration and urine, so if your items are absolutely clean, you'll worry less.  Our bodies constantly exude minute amounts of these attractive chemical tags, and just ONE wearing is enough to attract these pests. The larvae can leave large holes in natural materials.

Sawtoothed grain beetle
The adults, (the ones you usually see) are small, thin, dark brown insects less than a quarter inch long.  Sawtoothed grain beetles are major pests in factories, homes and granaries.  They feed on a very wide variety of products, flour, bread and cereal products,
macaroni, dried fruits, nuts, sugar and even improperly cured meats.  They are named primarily because of the six sawtooth-like teeth found on the two sides of the first segment behind the head, the pronotum.  

Sawtoothed Grain Beetles are very small, flat insects that easily hide in the cracks and crevices of food packages, can penetrate the packaging and infest the product inside. An adult female will lay, over her lifetime, almost 300 shiny white eggs in the food they are infesting.  Eggs hatch into tiny, yellow-white larvae, about an eighth of an inch long, and have three pairs of legs and a false pair.  A larva will molt as many as four times, and depending on conditions, will complete this cycle in slightly less than a month.  If conditions are not ideal, that cycle could take almost a year.

Sawtoothed Grain Beetles can develop into very large populations in stored food products, and the first sign you usually see, are the adults crawling all over your cabinets.  Adults feed on the same materials as the larvae, so they can keep on going, right there in your pantry.

Control is usually easy for the homeowner.  Clean everything out, vacuum thoroughly, as detailed above, and discard all infested materials - outside.  As far as using insecticides, you would need a residual - not Raid or Black Flag.  Might be cheaper and better to just paint the inside of your cabinet - if you can - and kill two birds with one stone.

Most of us see silverfish at one time or another.  These are one of the insects that can damage natural materials, cloth, paper, or book bindings.  If you have, say, a collection of old piano rolls, you are intimately familiar with silverfish.  They'll eat your whole collection in a hurry, if you're not careful.
So called because of its shiny gray appearance, most of us see a silverfish at one time or another.   These are one of the insects that can damage natural materials, cloth, paper, or book bindings.

These soft-bodied, wingless insects scurry about at night.  They are nocturnal and you won't see them in the daytime unless there's a heavy population or they're disturbed. They can easily climb rough surfaces, but not slippery surfaces, such as your bathtub or sink.  Torpedo-shaped, with three long bristles at the rear, they subsist quite happily in your attic, feeding mostly on starchy materials, book bindings, wall paper, cotton cloth and linens.  While not a serious pest, they can dispense with some of your stored treasures.

The female can lay over a hundred eggs, and places them in many favorable places, in cracks and crevices, and leaves them alone.  The nymph molts eight times, at which point they are able to reproduce.  The adults also molt throughout their entire lifetimes, enabling them to regrow lost appendages.  They are also quite long-lived, often living more than three years.

confused flour beetle
Flour beetles, most notably the Confused flour beetle and the Red flour beetle look very much alike.  A ten power glass is needed to tell the difference.  Slender, beetle-looking things, they are
reddish-brown and about an eighth of an inch long - about the size of a grain of rice. Both are major pests of flour and flour products.  They cannot penetrate nor feed on whole grains, but can be found in virtually any other processed food product.  This includes anything manufactured with flour products, dried fruit, spices, chocolate products and even tobacco products.  This is the pest you find most often in those too-old cake mix boxes.  And they can reproduce inside your cabinets if you don't do something about it.

Adult females will deposit as many as three or four of their sticky white eggs, per day, in the product itself, or in the cracks and crevices of packaging materials.  They can produce as many as 400 to 500 eggs in their rather long lifetime.  Eggs hatch in about two weeks and the tan colored larvae go through as many as 12 molts, reaching adult stage in about a month.  Ideal conditions produce as many as six or seven generations in a year.

Any product infested with these pests acquires a rather distinct odor (and flavor) as a result of secretions from their very active scent glands.  These two flour beetles are quite common.  Most homeowners see this problem happen every once in a while.

Image of riceweev.gif
The adults are about an eighth of an inch long, dull reddish-brown in color, with four red or yellow spots on their wing covers and irregular round pits on their pronotum.  The head is an elongated snout.

Rice weevils are primarily grain feeders, but will attack almost any kind of whole grain, as well as nuts, beans, and even some fruits.  The are more common in the southern states, but they can actually be found all over the world.  They are strong, accomplished fliers, and will fly from one field to another, infesting grains before the actual harvest.

The female bores a hole in the kernel and deposits an egg, and she can lay up to 400 eggs in her lifetime.  She seals the egg inside the kernel with a material she excretes, sealing the egg up inside the kernel.  The larva hatches within 72 hours, and then starts feeding, within the kernel, and molting four times before pupating.  The white, legless larva, with a dark head, are only found within the seeds they are infesting so you usually don't see them.  The entire life cycle takes only a month or so.

spider beetle
There are several kinds of spider beetles, the one pictured is the brown spider beetle.  They all look mostly alike, with the same

same oval body conformation, just different coloring.  Spider beetles are very small, less than three sixteenths of an inch long, with oval bodies, long legs and bodies covered with short hairs and rows of small pits running the length of their wing covers. The head is invisible, viewed from above.  They look like very small spiders.

Spider beetles can remain active during cold weather, and can be difficult to control because they also infest such a wide variety of products.  The larvae develop on the foods they eat and old storage buildings can harbor infestations in collections of stored products.  They can also bore into wooden and cardboard items to pupate.

Yellow meal worm
The rather large Yellow meal worm, are shiny black beetles, a half inch long, with well-developed wings, are accomplished fliers and are attracted to light.  They are named for the  larva, which are more than an inch long, hard-bodied and are bright yellow.
Seldom a pest in homes, they are, however, major pests in storage facilities, in dark, undisturbed locations.  They feed on these forgotten residues, overwinter in the larval stage and emerge, in the spring, to begin feeding on the food they are infesting.  The adults can lay up to 300 eggs and will live about three months.  The entire life cycle takes a year.

Since the larvae will often crawl away from the egg site, infestations can continue in other years.  Thorough clean up is absolutely required.

Fur beetle
The Fur beetle and the Black Carpet beetle are usually described together, the only difference is the Black carpet beetle has white or yellow hairs on the wing covers.

The larvae look hairy, with color bands, have a tuft of hairs at their posterior.  You can usually see the cast-off skins, which have the same banded appearance.  Larvae avoid light, and when disturbed, will "play possum" and remain immobile for a short time before resuming activity.

The larva will pupate, invisibly, at the last molt, right inside the last larval skin.  New adults will even remain inside the last skin for up to three weeks, before flying off to feed on the pollen and nectar of flowers.  The adult stage is attracted to light.

The adults are essentially outdoor insects, mate and feed on flowers.  After mating, the adult females seek out places to lay a total of almost a hundred eggs in any material that will support the larvae, such as bird nests, rabbit warrens and animal burrows.  With indoor situations, items such as woolens, rugs and curtains are at risk of infestation.

Indian meal moth
By far the most recognizable in our food supplies, the adult moth can have a wingspread almost five eighths of an inch wide are copper-brown and grey, are folded backwards in a resting position, showing copper and grey bands of color.
Adults do not feed on stored products, but the larvae will feed on any coarse flour, processed foods, whole seeds dog food and even red peppers and spices.  Adult moths lay their eggs directly on the material, usually at night, and over a two or three week period, will lay more than 400 eggs.

Indian meal moth larvae feed not only on coarse ground flour products, but also seeds and whole grain products, dried fruit, nuts, chocolate, beans and most products manufactured from these ingredients.  Indian meal moths are serious pests in both homes and other areas where food is prepared, stored or produced.

The larvae produce silken-type webbing throughout the material they're feeding on. Mature larvae move away from infested materials to pupate in neighboring cracks and crevices.  They can easily have six generations per year.  Homeowners often discover these infestations when great numbers of larvae are seen moving away from infested materials, sometimes dispersing over the entire room.

Because of their habit of moving some distance from infested products, an intensive cleaning routine is necessary to find and eliminate Indian meal moths, especially in a commercial setting.  Fumigations can then be necessary.

Varied carpet beetle larva
Adult carpet beetles are about an eighth of an inch long, and round in appearance.  The backs of the insects have much the same color scheme as the larvae.  The larvae have small, hairy, soft bodies about a quarter inch long, depending on the instar.  The larvae feed on a wide variety of foods, including carpets, furs, woolens, skins, stuffed
animals, leather, feathers, silk and many plant products.  The adults feed on nothing except pollen and nectar from flowers outside.

In spring and early summer, the adult will lay up to a hundred eggs, usually cemented to the product, or on furs, woolens or any dried natural or animal material.  The eggs hatch in about three weeks.

The larval stage can withstand a long period of no food, and can molt as many as 30 times.  They also prefer clothes or fabrics soiled with perspiration, body oils and urine. As with Black Carpet beetles, the adults will pupate in the last larval skin and use the last skin to hide in for as long as a month.

house cricket
The common house cricket, (they're big, they're black and they jump) is a familiar invader for most of us.  It enters structures through the many cracks and crevices that occur in all buildings.  House crickets will damage natural fabrics and materials placed in their environment.
House crickets can be as big as an inch.  They can last, almost indefinitely, in your house or basement, or in any building.  In the summer, they do prefer the outside, but when populations are high on the outside, you will get them inside.  In cold snaps, they often move indoors if they can find a way in.  And since they can complete their life cycle inside of a structure, you can have them all year long.  The adults produce a regular, irritating chirp with their wings, and then quit as you get close to their location.  

Females can lay almost thousand eggs, and place them in strategic places, such as cracks and crevices, behind baseboards and other trim.  In the wild, crickets produce only one generation a year, the eggs hatching in the spring and generally reaching adult stage in mid-summer, after about eight molts and about 30 days.  The female has a long slender tube projecting from the abdomen, used strictly for egg laying.  All stages are harmless to humans.

Most important for control is to eliminate high grass, leaves and other debris, from around your foundations.  Sealing those cracks and crevices also serves to help eliminate the problem.

Chemical control, your last resort, is with a residual insecticide, applied around the outside of the foundations, and, if the infestation is serious, to parts of the inside also.

                       Furniture Beetles
Furniture beetle
Adult Furniture beetles are found all over the world, are about an eighth of an inch long, with mottled yellow, white and black scales.  The underside is white.  They attack a wide variety of materials, including clothes, furs, feathers, hair, wool, tortoise shell, silk, dried and preserved animal skins and horns, and even dried cheese, dried blood,
and book bindings.  They also attack leather, cotton, linen, jute and even softwood, especially if it is soiled.

Adult females can lay 60 eggs, in places where larvae are able to feed.  The eggs will hatch in about two weeks, and the larvae develop over the next 60 days.  Larvae of Furniture beetles are about half that size, about a sixteenth of an inch, and covered with bands of stiff hairs giving them a bristle-like appearance.  Like others of this same type, they pupate in their last larval skin, and will emerge from the last molt in less than two weeks.

Naturally, the most important method is to find the source of type infestation.  These infestations are usually found when the homeowner finds the adults.  The larval infestation, the most important to consider, could be in any stored item, detailed above, especially in areas of minimum traffic.

After removing the source, Furniture beetles are controlled by residual insecticides, applied to the areas they frequent.  This procedure is best done by a professional exterminator.

Larder beetle
Larder Beetles are a good 3/8ths of an inch long and have a distinctive band of yellow-white across the upper third of their wing covers.  The
banded area has several (usually three) dark spots, symmetrically, on each wing cover. You can see, with the naked eye, that it also has clubbed antennae.  The underside of the body is covered with very fine yellow hairs.

Larder Beetles overwinter on the outside, enter homes and other buildings, usually in the spring or summer.  In addition to the things you normally think they might infest, they also infest cured meats such as ham, bacon, dried beef and fish, cheeses, animal skins, feathers, animal horns, skins, and stuffed animals.  They also are attracted to dead animals, or accumulations of feces.  

Adult females can lay about a hundred eggs during their lifetime, and place their eggs on ready food material.  The eggs hatch in a short time, about a week or ten days, and the larvae immediately bore into the food material.  They molt several times, five times for the male, six times for the female.  Just before pupating, they crawl away from infested materials and will often burrow into soft wood.

Few people cure meats in their homes anymore., so the problem is usually associated with inside infestations of mice or other rodents.  The beetles can seek out and find these animal carcases and this is when the homeowner can have a problem.  The bad news is that you will generally need the help of a professional exterminator to clear up this problem.  And it won't be easy.  It will take an extended program of insecticide applications to be sure this problem is entirely eliminated.

Lesser Grain borer
The adults are about an eighth of an inch long, with cylindrical dark brown or black bodies.  With a ten power glass, you can see the
tiny pits on their wing covers.  They are recognizable without magnification because their heads are bent downward and cannot be seen from overhead.  

Both adults and larvae are important pests of all kinds of stored grain.  Both attack and feed upon whole grains.  The larvae may also feed on flour products as well as whole grains.  Larvae complete development inside grain kernels.  Adults have very powerful jaws that can also bore into wood as well as whole grains.

The female can lay up to 500 eggs in her lifetime, making her quite prolific.  She lays her eggs, singly or in clusters, directly in the product.  Larvae will feed on grain products themselves, but can also bore directly into grain themselves.  The larva bores directly inside the kernel and pupates.  Adults have very powerful jaws and can bore into wood as well as grain.  They are not structural pests, however.

Control in residences are controlled by clean up and the application of residual insecticides.  Commercial establishments will generally need fumigants and a professional exterminator to control this problem.

Maize weevil
Maize weevils are mostly pests in the southern and temperate zones, in fields, of cereal grains mostly, but given a chance, will infest finished products.  The adults are accomplished fliers, but cannot
normally overwinter, outside, in the temperate zone.  They can survive a few hours at freezing temperatures and will survive in heated storage facilities.

The females lay their three to four hundred eggs by using their ovipositor to insert one egg into each seed or kernel.  Eggs hatch in a few days, and the larvae will eat the inside of their kernel, pupating inside.  The entire life cycle takes one to two months, depending on temperature.

Their life cycle takes no less than a month or so, and is quite similar to the Rice weevil. Maize weevils are larger and better fliers than the Rice weevils.

They are easily controlled by disposal of the product and a clean up campaign.  In commercial storage situations, fumigation may be necessary.

LINKS - Stored Product Pests

The Oregon State University manages a fantastic links page for stored product pests.
And from Kansas State University you can see their paper (.PDF format) about stored product pests infesting crafts and dried flower arrangements.
The EPA has published a paper (.PDF format) on the treatment of stored product pests with microwave radiation.  They have also published another paper on treatment with heat and diatomaceous earth.
The Canadian Department of Agriculture has a page with some more pictures of stored product pests.
UnExCo's OnLine General Store carries Gentrol, specifically a product for stored product pests, a "birth control" for these insects.

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