What Are Stored Product Pests?

Last Updated: June 7, 2021

Outside of Pest Control, you may not hear about these critters very often. You have probably had moths or beetles roaming around your home without knowing it. Food, such as grains, or clothes made of animal fibers, such as wool or fur, attract Stored Product Pests. Even though they can be a nuisance, in the wild these insects serve an important purpose by breaking down biological materials and fibers. There are several different species that fall into this category. In this article, we’ll discuss their habits in your home, and how you can prevent them from taking over.

Table of Contents

Food Pests vs. Fabric Pests

There are two main kinds of Stored Product Pests: those that infest foodstuffs, and those that infest fabrics. Within each group are many different species of insect that thrive in different environments. However, they do share common characteristics.

Food Pests seek grains or grain products, cereals, or flour. This group includes Drugstore Beetles, Cigarette Beetles, Spider Beetles, Granary Weevils, and Indian Meal Moths.

Fabric Pests enjoy a wide variety of different fabrics, including cotton, wool, animal fur, hide, hair, and silk. This group includes Carpet Beetles, Webbing Clothes Moths, and Casemaking Moths.

Other pests such as Silverfish, Firebrats, Book Lice, and Mites may go after both foodstuffs and fabrics. Because these insects are so versatile, it is important to cover all of your bases and seek preventative measures to protect your home.

Beetles

A varied carpet beetle on a white background

Carpet Beetles

Carpet Beetles are quite common here in the Pacific Northwest. They feed off of many different food sources, including both food and fabric. This makes them likely to end up inside your home at some point. In fact, you may have a few tucked away in your house right now!

Carpet Beetles are small, oval-shaped, often mottled or spotted in pattern, and vary greatly in color. They’re between 1/16” and ¼” long depending on the species. You can identify them in their larval stage: a long, hairy body with distinct tufts of hair at one end. Here in Washington, you may encounter the Varied Carpet Beetle, Furniture Carpet Beetle, or Black Carpet Beetle.

Adult Carpet Beetles can and will fly in from the outdoors, probably by accident. It is also common to carry Carpet Beetles in from your garden on flowers or plants. Many adults feed on pollen, but will enjoy animal proteins like fur, wool, feathers, trophy animals, and some grain products.

Carpet Beetles require vitamins and minerals, and may also frequent wool with bodily oils or stains, pet food, dead insects, seeds, fertilizers, or stored products such as cereal or noodles. Larvae live and grow in environments that are hidden. You can find them in dresser drawers, behind baseboards, in closets, or around areas where dust, hair, lint, crumbs, or insect carcasses collect.

carpet beetle larva on a blank background

Carpet Beetles are often confused with Bed Bugs or Ladybugs. Aside from potentially causing an allergic reaction, though, Carpet Beetles are not harmful, and we consider them to be a nuisance pest.

Drugstore Beetles and Cigarette Beetles

Drugstore Beetles and Cigarette Beetles are similar, and it is easy to get them mixed up. You can frequently find both here in the Pacific Northwest, usually in warmer areas or inside buildings.

a cigarette beetle taking flight
A drugstore beetle on a piece of paper

They vary slightly in size, but are generally ⅛ inch long. Both Drugstore Beetles and Cigarette Beetles are medium to dark reddish-brown. The Drugstore Beetle has distinct lines or grooves on its forewings, while the Cigarette Beetles does not. 

Both of these Beetles can burrow through wood in order to get to food sources. Drugstore Beetles are usually on the lookout for dried pet food or spices, both of which are common causes of infestations. Cigarette Beetles have a wider food range. As their name suggests, they will frequently attack tobacco products.

Neither are aggressive towards people. Infestations are normally caused because food or tobacco products are  not properly stored in areas with high humidity. Infested foodstuffs should be thrown away, but salvageable items can be placed in a freezer for 16 days at 36°F or seven days at 25°F, according to the University of Florida.

Spider Beetles

Spider Beetles get their name from their round, globular shape and long legs. They range anywhere from 1/16 inch to ⅛ inch long. Color can vary widely depending on the species, but they may appear black, brown, red, orange, or somewhere in between. Unlike other “bran bugs,” they can withstand a colder temperature. In fact, as long as there is adequate humidity, these Beetles can be active at temperatures below freezing.

a spider beetle on a white background

Spider Beetles feed on a wide range of foodstuffs, including (but by no means limited to) corn meal, beans, spices, dried fruits, flour, grains, seeds, or wheat. They may also be attracted to insect carcasses, feathers, hair, old wood, silk, fabrics, and wool.

It is common to encounter Spider Beetles when sanitation is poor or in places where food has been standing for a long time. It’s important to note, though, that other pests will probably get there first.

You might not notice them right away because they are active at night. Infestations can be difficult to tackle due to their varied food range, but keeping things generally clean and storing foods and fabrics in pest-safe containers will help prevent problems from arising.

Moths

Indian Meal Moth

Indian Meal Moths are the most common Moth found infesting foodstuffs. The Washington State University Manual for Pest Management Professionals regards them as “handsome moths,” and we have to agree. You can easily identify them by their pattern: a reddish-brown outer forewing, and cream colored inner forewing. These Moths have roughly a ¾ inch wingspan.

Indian Meal Moth

Female Indian Meal Moths lay 100-300 eggs. These eggs hatch after a few days, afterwhich small, whitish caterpillars emerge. The larvae feed on grains, dried fruits, or nuts. When fully grown, larvae are about ½ inch long. They are off-white with a pink or green hue. The larvae, having eaten, spins a silken cocoon and transforms into a pupa. This pupa is usually light or medium brown. When the weather is warm, this cycle takes 6-8 weeks.

A webbing clothes moth on a white background

Webbing Clothes Moth and Casemaking Clothes Moth

The Casemaking Moth is the most common infesting Moth in Washington. It is mainly attracted to clothing and materials of animal origin, but may be found infesting spices or tobacco products.

These Moths look and behave similarly, but small details allow us to distinguish between the two. The Casemaking Moth is smaller and darker than the Clothes Moth, with three spots on its wings. It’s larva carries a silken case wherever it goes (hence its name). This species is more common in homes.

A casemaking clothes moth on a grey background

The Webbing Clothes Moth is attracted to fabrics only, mainly those of animal origin such as furs. Its larva spins a silken tube or mat that it feeds on as it grows. Both Moths are small, only ½ inch long. Both have distinctively narrow wings that are lined with fringed hairs. The larva of each is light, cream-colored with a darker head. Larva are about ⅓ inch long.

Other Pests

Silverfish and Firebrats

These primitive-looking insects may look scary, but are not harmful. Silverfish (pictured left) and Firebrats (pictured right) can look quite similar, and are usually grouped together. Both have a silvery or pearly-grey coloring and possess 3 long “tails” or appendages at the backend of their bodies.

A silverfish on a white background

Both species of insect can be found infesting dried foodstuffs such as flour, starch, sugar, or glue. They have versatile food preferences, though, so you may encounter them damaging linens like cotton or wool.

Firebrats that are found in Washington usually thrive in hot, moist areas. Be sure to inspect boiler rooms, kitchens, and bathrooms for activity. Silverfish are the opposite. You’ll likely find them in cool, damp places like basements or crawl spaces.

Regardless of which insect you encounter, it is possible for both to be present. Silverfish and Firebrats (along with many of the pests we have already discussed) are attracted to high moisture levels. Ensuring proper ventilation and dehumidifying storage areas will help prevent activity.

A pile of small beige grain mites

Mites

Mites are frequenters of homes and gardens, and it isn’t uncommon to find large quantities of them in areas where moisture and sanitation has become an issue. They are extremely small, 8-legged pests that are hard to identify without a microscope. Mites tend to be opaque, light yellow, or light tan. As they may appear in large numbers, it is easy to mistake them for a pile of dust.

Mites feed on a variety of foodstuffs such as grains, seeds, flours, cereals, fruits, tobacco, sugar, dry pet food, mold, paper, or organic debris. They generally prefer high humidity and temperatures between 65 and 75 degrees. However, they are more prevalent during the colder months.

While Mites are not outwardly threatening, consuming contaminated food and prolonged skin contact can be damaging or cause irritation. Following the tips in the Prevention section of this article will help lessen the likelihood of recurring issues and infestations.

Book Lice

Book Lice are pale, wingless, soft-bodied insects that are difficult to see without aid. While they do resemble head lice, there is no need to fear. Book Lice are usually after flour, grains, or bookbinding glue (hence their name).

Several book lice in a pile of rice or grains

These pests thrive in damp, dark, protected environments. A wet basement full of poorly stored items is a breeding ground for these critters. Due to their reliance on moisture, control can be obtained by using a dehumidifier.

Granary Weevils

The Granary Weevil is not a terribly common pest, but it is easy to recognize by its distinct weevil snout. This species is found here in Washington, and is a dark brown or black color. It is usually 3/16” long.

Granary Weevils appear to have wings. However, they do not have functional wings beneath their wing covers and cannot fly. They are attracted to intact grains as opposed to processed grains, and can produce 2 to 10 generations a year depending on the weather.

Prevention and Control

The most effective measure you can take to stop these stored product pests from establishing themselves in your home is to clean regularly and regulate the humidity inside the structure. Moisture and unsanitary conditions will provide these pests with food, harborage, and an environment in which to grow. You can also refer to this handy Pantry Pest Guide for on-the-go information about common Stored Product Pests.

How Sunrise Can Help

We offer a maintenance service to help with all kinds of pests, including Beetles and Moths. All Pest Protection is a quarterly maintenance service aimed to prevent infestations of general pests such as Carpenter Ants, Rodents, Bees, and other insects. We come out on a 3-month rotation to provide an exterior perimeter spray where the home and foundation meet, spot treat around doors and windows for activity, sweep reachable webs and Spider egg sacs, and maintain Rodent Bait Stations (secured, locked, black plastic boxes) on the exterior of the home to mitigate outside Rodent populations.

All Pest Protection (APP) also can include various warranties for general pests, which are established after the Initial Inspection and Treatment. Once you get started, each quarterly service is only $99 before tax. Should your house be overrun by Fleas, Bees, or Spiders, or any of the pests eligible under your warranty, all you would have to do is give us a call. We’ll dispatch a Technician to complete a pest-specific treatment at no cost to you under your APP Warranty.

Sources

Antonelli, Arthur L. Pest Management Study Manual for Pest Control Professionals. Washington State University Extension, 2016.

“Featured Creatures.” Drugstore Beetle – Stegobium Paniceum, University of Florida, entnemdept.ufl.edu/creatures/urban/stored/drugstore_beetle.htm.

“Silverfish and Firebrats.” National Pesticide Information Center, npic.orst.edu/pest/silverfish.html#:~:text=Silverfish and firebrats .

“Spider Beetles.” Penn State Extension, 28 May 2021, extension.psu.edu/spider-beetles.

About the Authors

This article was created and edited in collaboration with multiple licensed pest control technicians, experts, researchers, and authors.

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