I got some similar recently. I didn't think about the sun shining on them during the day. Frigging melted (warped) them beyond working. It was one hot August this year ! But, I've pretty much eradicated everything around here. Trapping season brought me 3 rats, 4 mice, and no telling how many from bait. They ate up 12 oz. over a 4 week period. Thank God we never got any inside.