STORED GRAIN INSECTS

A. FARM STORED GRAIN

1. WHAT TO DO BEFORE HARVEST
a. SANITATION. Thoroughly clean all grain residues from bins. Remove all residues from areas around the bins and any nearby feed bunks or storage. Remove all grain residues from combines, trucks and augers. These residues will be the main sources of insect infestations for farm stored grain. This is a very important part of grain management.

b. RESIDUAL SURFACE SPRAY. After all debris and grain residues have been removed, an application of a residual insecticide should be made to the complete inside of the bin. This insecticide should also be applied around the exterior and to all areas where residues were removed. Spray all surfaces until wet; usually one gallon will cover 1,000 square feet. The labeled effective compounds are:

1. Methoxychlor - A 2.5% solution made by mixing 3/4 pint of 25% methoxychlor emulsifiable concentrate per gallon of water.

2. Chlorpyrifos-methyl (Reldan 4E) - A solution made by mixing 4 fluid ounces of Reldan 4E in 3 gallons of water.

3. (RU) Cyfluthrin (Tempo 2 or Tempo 20WP) - Follow label instructions and mix a 0.05 percent active ingredient concentration. Restricted for pest control operators and commercial use.

c. FUMIGATION OF EMPTY BIN. Thorough cleaning of some bins may be impossible. If the residues cannot be removed or penetrated with the residual spray, the bin may be sealed and fumigated. Aluminum Phosphide is commonly used for fumigation. It is a restricted use insecticide and should be used only by those trained and certified specifically for this product.

d. CONTROL RODENTS - Make bins as rodent and bird proof as possible. Use rodenticides regularly around the bin. DO NOT use rodenticide in the bin.

e. NEVER ADD NEW GRAIN TO BINS WITH OLD GRAIN. DO NOT store new grain close to left-over grain unless the insects have been eliminated.

2. GRAIN MANAGEMENT FOR INSECT CONTROL

Consult the Agriculture Engineers for methods to properly manage grain. Good grain condition for long term storage will greatly reduce or eliminate insect problems. Stored grain moisture should be 14% or less. The temperature of the grain mass should be within 20°F of the average outside air temperature. This temperature requirement can be met by cooling the grain to 40°F in the fall and warming the grain to 60°F in the spring.

3. INSECT CONTROL - The use of grain protectants at time of harvest is justified if grain is to be stored for more that 3-6 weeks at temperatures above 60°F, or if summer harvested grains will be stored longer that one month, or if fall-harvested crops will remain in storage beyond May or June of the year following harvest. All protectants should be applied after high-temperature drying of the grain has been completed.

Producers should monitor stored grains regularly to assess grain moisture, temperature, and determine whether insect pests are present. Grain masses should be monitored a minimum of once each month during the winter months of November through April and at least twice each month during the summer months of May through October. Areas of the grain mass most frequently infested include the grain surface and the central core. Special attention should be given to these areas when sampling, but other areas of the grain mass should not be ignored. Insect pests in stored grains can be sampled by a variety of methods including deep bin probes from several sections of the grain mass, probe traps, sticky pheromone traps, and by direct observation. Several of these methods may be needed to detect insect infestations in a stored grain mass.

a. GRAIN PROTECTANTS. Labeled insecticides may be applied to grain before or as it is being elevated into the bin. Insect populations are greatly reduced or prevented by using these materials. The recommended and labeled compounds to be used are:
1. Chlorpyrifos-methyl (Reldan 4E) - Dilute Reldan 4E with water per directions on label and apply to the moving grain stream to give a deposit of 6 parts per million on the grain. Reldan 3% dust may be applied at 10 pounds per 1,000 bushels of barley, oats, rice, sorghum, or wheat. Reldan IS NOT labeled on corn.

2. Pirimiphos-methyl (Actellic 5E) - Dilute Actellic 5E with water per directions on label and apply to the moving grain to give a deposit of 6 to 8 parts per million on the grain. Actellic is labeled on corn and sorghum and IS NOT labeled on small grains.

b. LEVEL GRAIN SURFACE. After the protectant is applied and binning is complete, LEVEL the grain surface. Leave at least 6 inches of space between the top of the leveled grain surface and the top of the bin wall.

c. SURFACE TREATMENT. When bin fill is complete, when the grain is in condition for storage, and when the grain surface is level; an insecticide should be applied to the surface to form a barrier to prevent infestations. A surface treatment should be applied to all grain.

Insecticides labeled for surface applications are:

• malathion on corn, wheat, oats, rye, barley, sorghum, and sunflowers;
• chlorpyrifos-methyl (Reldan) on wheat, oats, barley, rye, sorghum, and sunflowers;
• pyrethrins plus piperonyl butoxide on corn, wheat, oats, barley, rye, sorghum, and sunflower;
• Bacillus thuringiensis, a biological control compound, on corn, soybeans, wheat, oats, barley, rye, sorghum, and sunflowers; and
• Pirimiphos-methyl (Actellic 5E) on corn and sorghum.

The Indian meal moth, a surface feeding moth, is resistant to control with malathion. If this insect is a problem other surface treatments will have to be used. The biological control compound Bacillus thuringiensis is labeled for control of the larvae of this insect and could be used with malathion. Dichlorvos strips (Vapona) are labeled to be used in the space above all stored grains for the control of flying insects, including adult Indian meal moths. One strip per 1,000 cubic feet of air space above the grain should be used and changed every 6 to 8 weeks.

1. Granary weevils cannot fly. Eggs are placed inside whole kernels. Damage is caused by the larvae feeding in whole grain and the adults feeding in and on whole or broken grain.
2. Saw-toothed grain beetles seldom fly but both the larvae and adults feed on cracked or broken grain, flour, meal, breakfast food, stock feed, candy, and dried fruit. The thorax, the body region behind the head, has saw- toothed points on both sides.
3. Larvae and adults of the red flour beetle and a closely related species, the confused flour beetle, feed on flour, grain dust, and broken grains.
4. Larger cabinet beetles and several closely related species are general feeders on grain and grain products. They will also feed on material of animal origin, such as hides.
5. The eggs of the lesser grain borer are placed on kernels and the larvae bore into the kernels. The adults can fly and also feed on grain.
6. Rice weevil adults can fly. Eggs are laid inside the kernel. The larvae feed in whole grain while the adults will feed both in and on grain.
7. Indian-meal moth larvae spin webs on the surface of grain and feed on kernels enclosed within the webbing. The larvae will also spin webs on sacked grain in storage areas.
8. Cadelle larvae and adults feed on whole grain. The larvae bore holes in the wood within bins where they hibernate. This is one of the largest stored grain insects.
9. Flat grain beetles are one of the smallest common stored grain insects. It Is usually found associated with out-of-condition or insect damaged grain.
10. Angoumois grain moth eggs are laid on the outside of the grain. The larvae bore into the grain and feed within the kernel. Adults may fly from granaries and infest corn in the field.

For control recommendations in farm bins see UMC Guide 7100, "Insects in Farm Stored Grain-Their Prevention and Control." For control in kitchens see UMC Guides 7374, "Angoumois Grain Moth and Indian Meal Moth;" and 7376, "Saw-toothed Grain Beetle, Confused Flour Beetle, and Red Flour Beetle." These are available at your county University Extension Center.