What are your nightime temps right now? If you only have a couple bugs found in the screenings right now, they haven't really had time to establish themselves. I'd turn on the fans and get the grain cooled now. Truth of the matter is, when they really multiply and thrive, is when their environment is around 90°. When there are enough of them, they can make their own heat. I've been in bug infested bins in the middle of winter, and standing in the grain is just like standing in a tub of warm bath water. Having a little aeration in the bin would have cooled that and killed the bugs. Still see guys with air in the bins that will add Phostoxin pills instead of turning on the fans.

If you think you have an infestation under the floor, turn on the fans and let them run when its cold outside. You also might see if you can get a positive ID on what kind of bugs are in the grain. In this area, out biggest problem is the lesser grain borer. They are resistant to the commonly used protectants.