The Pests

Stored-Product Pests in Dry Storage: Meal Moths, Grain Beetles, Flour Beetles and the Cigarette Beetle

Written for: Kitchen managers, dry-storage leads, bakers, anyone who buys in bulk

Parts of this page marked Professional synthesis, not law are a Board Certified Entomologist's reading of published records. They are not legal rules, they are not legal advice, and they are written to read the same for an owner, a customer, or either side's counsel.

A small moth fluttering in dry storage, a tiny flat brown beetle in the flour, webbing in a bag of rice: these are stored-product pests, and they are the one pest group that does not come from the building. They come in the product, and they stay in the product. The program is a search of the shelves, not a treatment of the room.

Who they are

Several species of beetles, including the warehouse beetle, sawtoothed grain beetle, red flour beetle, and cigarette beetle, commonly attack a variety of foods. — UC IPM, Pest Notes: Pantry Pests

The most common species of meal moths found in the home pantry is the Indian meal moth, Plodia interpunctella. — UC IPM, Pest Notes: Pantry Pests

The grain beetles “lay eggs on stored food products, especially of high moisture content” (Utah State University Extension, Grain Beetles). The drugstore beetle is a “common pest of stored food in homes and storehouses” (Utah State University Extension, Drugstore Beetle), and the cigarette beetle, despite the name, is found in spices, dried chiles, flour and dry pet food as readily as in tobacco.

Finding the source

Professional synthesis, not law. The adults you see are the end of the story. The larvae are in a bag or a box, and that bag has been there a while. Start with the oldest stock and the open containers: flour and meal, rice, oats, dried beans, nuts, spices and chile powders, cocoa, dry pasta, bird seed or pet food if any is kept, and the sweepings behind the shelving. A bag with webbing, clumping, fine dust at the bottom or small holes in the paper is the source. Bag it, take it outside, and look at what was next to it.

Then

Clean up all spilled food products and food storage shelves and storage areas in general. — Utah State University Extension, Indian Meal Moth

Store food and bulk goods like pet food in containers with tight-fitting lids, not plastic bags. — UC IPM, Pest Notes: Pantry Pests

Inspect all incoming food items for pests. — Utah State University Extension, Indian Meal Moth

Use a pheromone trap labeled for pantry pests. — UC IPM, Pest Notes: Pantry Pests

In a restaurant that means: vacuum the shelves and the floor and the cracks in the shelving where larvae pupate, rotate stock first-in first-out, decant open product into lidded bins, check the delivery before it goes on the shelf (Delivery Inspection Card), and hang a pheromone monitor for the meal moth so you can see the count fall. The monitor is the proof that the source is gone; if the count does not fall in two or three weeks, a bag was missed.

Insecticide has almost no place in this. The pests are inside sealed food, where no spray reaches and where no product is labeled to go. A store-bought aerosol in dry storage is a critical citation and does nothing for the larvae in the flour (who may apply pesticide).

Not sure which beetle you have? Text a photo to (801) 477-0223. The answer changes which shelf to search.