My cats play and torture roaches until they die. They are not purposely trying to kill them (at least, I don't think)...they just torture them until they die - then they leave them there. They won't eat them. Why? I thought it would be nice if they purposely kill the roach (my own pest control) - but it doesn't seem to want to kill it... it just plays with it...then leave its carcass there. I mean, maybe it eats some of it - I don't know...sometimes I find half a roach carcass. Why do they do this?