I live in Alaska and can pick up a whatever that has fleas, a week after it dies, take it home, put in my deep freezer at minus -10 below zero, pull it out a week later to thaw, and will have flea's coming to life like you wouldn't believe. You cannot freeze a flea to death, in my opinion. So, now when I take them out of the woods, they go in a bag filled with Raid, then home to the -10 below freezer, then let them thaw inside that Raid bag. Look in the corner of the bag, those are all dead fleas, lot's of them. Remember the thing was dead in the woods for a week before I picked it up. They are comatose until they warm up. This is real life experience, I didn't read it somewhere, I do it, everyday. I didn't listen to to others when I first started either, and got a lot of flea bites. Doesn't make sense that they will live through that, but they do. Can't argue with real life results. Now somebody will post something they read off the internet and think they are right because the saw it on their phone. Their is some crazy info. posted above, probably from a phone, not a real trapper that is for sure.