Insects indoors (in the cold months) are usually there by some weird accident--as far as they know they've found themselves in an uncommonly warm cave, but once they're in they find themselves lacking food and unable to get out. Most insects have such short life spans that I try not to feel bad about them starving or dehydrating in my house. Creatures that bother my wife will be chucked outside, which (in the cold months) is probably also a death sentence.