The other option is to fumigate the bin. Unfortunately, there are no easy rules to help you decide exactly when to fumigation because there are few good thresholds. Another suggestion is that if one live primary pest is found per trier sample or if several insects are collected within 24 hours in probe traps, then fumigation is justified. Some additional notes about fumigation Fumigation penetrates the grain and kills even primary feeders inside kernels. But fumigants dissipate quickly, and thus reinfestation of the grain can occur if the bin is not well sealed to prevent insects from getting inside.
Fumigation can be dangerous.
Aluminum phosphide, the most common grain fumigant, is very toxic. It is highly reactive with water, and can explode if handled incorrectly. Its various formulations require special handling, special protective equipment, and specific application procedures on the label. In Michigan, a commodity fumigation standard is required in addition to your private or commercial applicator license to do fumigation. If you don't have the training, don't do the fumigation.