Clean, cool, dry storage areas are preferred. Avoid storing food in open containers on shelves. Keep food storage areas free from spilled food and food particles. Good housekeeping helps prevent insect infestations. To prevent or at least minimize insect infestations in stored food products it would be ideal to store them somewhere between 35°F and 45°F. Realistically, if they can be stored below 65°F it will be helpful.

Insects and Animals

In the best interests of the family budget, food conservation, clean food and health, stored food items should be protected from contamination and damage from insect pests.

Small flour beetles, dermestids, weevils, larder beetles, several kinds of moths and other stored food pests readily infest, contaminate, destroy, and consume accessible food supplies. It is important to prevent or reduce these kinds of losses whenever possible.

Prevent Insect Infestations

To prevent insect infestations in bulk foods, keep all stored foods in tight, clean, metal, plastic, or glass insect-proof containers that have tight fitting lids and no open seams or crevices. Store food off the floor and away from damp areas.

Fumigation with Dry Ice Prior to Storage

To fumigate home stored wheat or similar products, spread about 2 ounces of crushed dry ice on 3 or 4 inches of grain in the bottom of the container, then add the remaining grain to the can until it is at the desired depth. If fumigating large quantities use 14 ounces for 100 pounds of grain or 1 pound of dry ice for each 30 gallons of stored grain. At approximately 75 cents a pound for dry ice the cost of fumigating is reasonable.

Since the fumes from vaporizing dry ice are heavier than air, they should readily replace the existing air in the container. Allow sufficient time for the dry ice to evaporate (vaporize) before placing the lid on all the way (approximately 30 minutes). The lid should not be made tight until the dry ice has pretty well vaporized and has replaced the regular air. Then it can be placed firmly on the container and sealed.

Should pressure cause bulging of the can after the lid has been put in place, remove the lid cautiously for a few minutes and then replace it. If using plastic bags in the can, don’t seal the bags until the dry ice has vaporized. Carbon dioxide will stay in the container for some time, provided the container lid is tight. When practical, follow the above procedure in a dry atmosphere to reduce the condensation of moisture in the bottom of the can.

Dry ice tends to control most adult and larval insects present, but probably will not destroy all the eggs or pupae. If a tight fitting lid is placed firmly on the container after the dry ice has vaporized, it may keep enough carbon dioxide inside to destroy some of the eggs and pupae. After 2 to 3 weeks another fumigation with dry ice may be desirable to destroy adult insects which have matured from the surviving eggs and pupae.

If properly done, these two treatments should suffice. Yearly treatments are not indicated unless an infestation is recognized.

Caution: Dry ice should always be handled with care. It should not be accessible to young children or to adults who are not aware of its vaporizing properties.

Chemical Control in Insect Infested Areas

If the infestation is extensive, dispose of the contaminated food. If the infestation is light, you may be able to salvage the product, but in most cases it will be to your advantage to dispose of any insect infested food you have in storage, including spices.

Remove all food packages and containers from the infested area. Clean the shelves, and as appropriate, remove the lower kitchen drawers and clean the areas behind and underneath the drawers with an extension to the vacuum. Then spray the area with a household formulation of an approved insecticide such as pyrethrum or Malathion. If an aerosol formulation is used, the dosage should be no problem. If mixing a concentrated insecticide with water, follow label directions. Spray cracks and crevices under shelves and along mop boards. Do not spray the insecticide directly on food, food preparation surfaces, such as bread boards, or on any food equipment or utensils. If appropriate, once the spray dries, cover the
shelves with clean shelf paper or foil before returning food packages to the shelves.

Kerosene-based sprays should not be used around flour since the flour may absorb the kerosene. If treating an area where flour is stored, remove the flour before treating and place it back on the shelves after the kerosene odor is gone. Do not spray oil-based insecticides on asphalt-tile floors.

Household formulations of Diazinon, Baygon (propoxur), Malathion, or Drione, may be used for crack and crevice treatment behind radiators, under sinks, and in ant runs to destroy ants, roaches, earwigs, silverfish and roaming flour- infesting insects.See label directions for information on insects controlled by these chemicals and the appropriate uses.

NOTE: Most insecticides are poisonous to man and animals. Follow instructions on the label. Do not store pesticides near foods or medicines. Keep all pesticides out of the reach of children, pets, and livestock.

Physical Methods of Controlling Insects in Food

Clean, cool, dry storage areas are preferred. Avoid storing food in open containers on shelves. Keep food storage areas free of spilled food and food particles. Good housekeeping helps prevent insect infestations.

Deep Freeze Control for Grain

Small quantities of grain, 1 to 10 pounds, can be put in medium to heavy food grade plastic bags and placed in a deep freeze for 2 to 3 days. This will usually destroy all stages of any insect pests which are present.

As a check spread the deep freeze treated grain on a cookie tray at room temperature until thawed. If live insects are present they will probably be seen crawling about. If they are present, repeat the process. If not, remove any insect fragments, put the grain in an  approved container and store it in a cool, dry place.

Heat Treatment – Air

When packaged goods such as beans, cereals, whole grains, nut meats, and similar dried foods become infested they may be “sterilized” by heating in an open oven as follows.

Spread a shallow layer of wheat in a cookie tray or large pan. Pre-heat the oven to about 140° to 150°F. Put the tray in the preheated oven and leave it there for 30 minutes or more. The oven door should be left slightly open to avoid overheating. This treatment should destroy all stages of the insect if the layer of grain on the tray is not too thick (1/2 inch). Next, remove the tray and cool the wheat thoroughly before returning it to a clean, dry storage container. As necessary, use a fan to blow off any existing insect fragments. Where large quantities of dry food are to be treated, this method is not practical.

Heat is detrimental to the proteins in wheat and may reduce the ability of the bread to rise properly. Some reduced loaf volume and heavier texture may be apparent when using heat treated grains.

Dry Ice

Food may be fumigated with dry ice as previously described.

Bay Leaves, Chewing Gum, Chanting Words and Phrases

We receive numerous inquiries asking about exotic treatments to prevent insect infestations in stored grain. In unofficial experiments we have conducted, it was noted that some insects will continue to feed when enclosed in containers with tight fitting lids, even in the presence of these exotic suggestions. We have also concluded that chanting words and phrases fall upon deaf ears. Some consumers have reported on the effectiveness of many exotic treatments. Our investigations have shown these instances to only be effective when no insects were initially present in the food.