will a frost kill fleas? 0 Would a first frost kill off all fleas? We have a 10 year old cat that has never been outside. But we now have a gated backyard she will be able to go outside without any fear of losing her. More on will a frost kill fleas? Tags: cat, cold weather, flea larvae, flea problem, frost, hard freeze, kill, kill fleas, pupae, way Spread the Word! Facebook Google+ Twitter Pinterest Email Print Delicious Digg Fark Google Instapaper LinkedIn MySpace Newsvine Pocket Readability Reddit StumbleUpon Tumblr Yahoo!