Controlling Grain Pests

'A Purdue University professor used to say: "Every bin owner should be inside each bin every two weeks during the winter months and every week during the fall, spring, and especially after July 1 in the summer. Anything less is risky and poor grain management."

"You should know what to look for. Use the old poke, feel, look and smell test. Poke the grain mass with a metal rod and your arm to check for caked grain and hot spots. Feel the grain surface to see if moisture is causing kernels to stick together. If you smell something rotten, you should have been looking earlier. Check the roof to see if there is moisture or condensation."

Traps are also available which can be inserted into the grain to capture feeding insects. An insect like the granary weevil which feeds on whole, sound grain is more serious than are scavengers or secondary insect pests like the foreign grain beetle, flat grain beetle or the red flour beetle. Insects, like the foreign and flat grain beetles, are indicative of spoiled grain that contains mold or fungus.

Empty bins can be treated to reduce the likelihood of insect infestation. Tempo WP is the most commonly used insecticide for this treatment and has replaced many uses of malathion. Tempo WP has good persistence in dusty bins and on the perimeter of grain facilities.

High temperatures decrease the effectiveness of Tempo WP. Red flour beetles exposed at different time intervals on concrete treated with Tempo WP showed different results depending upon the temperature of the concrete. At 77°F, beetles began to survive at the end of two weeks and by 8 weeks survival was at least 90%. At 68°F, beetle survival remained below 5% for the entire 8 weeks. These results indicate that Tempo WP may have to be applied more frequently during the warmer months or in warmer climates to control the red flour beetle.

Other species of grain-infesting insects have yet to be tested, but similar results would be expected.