Facts About Foreign Grain Beetles

Adults of the foreign grain beetle are attracted to fungi and molds, where females deposit their eggs singly or in small clusters. Larvae emerge in four to five days at optimal temperatures (eighty-ninety degrees F). The larvae develop through four to five larval instars in about fifteen days. The adults have an average lifespan of 215 to 250 days. In their natural environment, both the larval and adult stages feed on molds growing in high humidity environments. The insect is a strong flyer and, from long distances, can easily locate moldy grain in bins and in fields.

The beetles themselves do not cause direct damage to stored products since their food is mold. If your grain or stored commodity exists in high humidity and has mold on it or in the storage facility, it will attract foreign grain beetles quickly. The real problem in the grain bin or warehouse is poor humidity management. When grain is placed in storage and not monitored periodically, moisture from condensation or high humidity can accumulate in the facility and molds will develop. This can occur even if the grain was originally dried below thirteen to fifteen percent moisture when inbound. The presence of molds and insects in the grain can result in rejection of sale or reduced market value. At the end of the day, the loss in revenue and possible loss of vendors and customers is the major problem. In the food supply, the presence of the beetles, even though they aren’t directly impacting the economic value of the commodity, can significantly impact the product since it will be considered adulterated. Therefore, foreign grain beetle management is still important.

Fumigation will completely take care of the foreign grain beetles that have made their way into your grain. From there, though, control of foreign grain beetles begins with good environmental management. Before new grain or product is placed in a bin or warehouse, respectively, the bin/warehouse should be thoroughly cleaned to remove old grain from the walls, floors, and augers. Harvest equipment should also be cleaned before use. If possible, the grain should be screened to remove broken kernels and other contaminants. After placing in a clean bin or warehouse, check the humidity levels at two-week intervals during warm months and one-month intervals during cooler months. Continuous monitoring for wet areas, mold growth, and/or insects is recommended. If any of these conditions exist, the grain or product should be aerated to lower the moisture level and temperature. In warehouses, proper ventilation is key!