Chuck,
I've yet to find a camera that will work with bats. The problem is not only do you need motion, but also a certain amount of heat to trigger then sensor to trigger the camera. Then, based on the camera you can have anything from a 1/5" second (Reconyx) to 1.3 seconds (Covert) before the picture is even taken. You also need to decide if you want the thumbnail image sent to your phone (cellular cameras only) or if it is fine to let the camera sit and then review the memory card. Next, decide if you need picture only, picture/video, or picture/video & audio. Lastly, you need to decide if you want white flash, infra-red, or black infra/LED use for taking images in low light situations.
After you've decided on what will be helpful, then you can start shopping for cameras that fit those criteria. Without a doubt, the best cameras are made by Reconyx, but they also come with the highest price tags. On the cheaper side of the scale will be the white flash cameras and then the entry level IR with picture mode only. It may be that you already have the best camera for how you want to use it. (Note: the latest issue of WCT Magazine has an article on the cellular trail cameras.)
Once you've got your camera(s), make sure you are familiar with flash distance, trigger speed, and trigger sensor locations. For watching flyers in an attic, it may be more helpful to do 30-60 second videos. As swampdonkey stated, the whiteness is most likely caused by the camera using too much fill light so either move the camera back or see if you can adjust it. If you're seeing the white flashes and the camera is located outside of the structure, you may be picking up moths or leaves (this is where video mode is very helpful) instead of the flyers. Over all, I'd recommend using video mode if you have it along with positioning the camera further away from the potential entrance and maybe even turning it so that the potential entrance isn't a straight 90 degrees to the lens.
