I never kill ladybugs, although I must admit I've never had to deal with hundreds of them in my house either. The few that manage to come in I just let be for their winter hibernation. They do no harm [I've read] and I've yet to notice any, hmmm, little brown "spots" anywhere either. They're wonderfull for the garden and some farmers even 'import' them for their fields [I've read].
My neighbor told me the orther day that hundreds of them hibernate in his birdhouses during the winter. I've even seen 'ladybug houses' for sale at the Meijers store.
All my ladybugs seem to be the Asian variety [more golden orangey with various spottings and some have no spots at all]. Question: whatever happened to all the red American type beetles? They've just seemed to have all disappeared [in my neck of the woods anyway]! Anyone know???