A controversy on Photocritic about insect killing for photographic purposes. I think killing bugs for photography used to be far more common back in the days of slower film emulsions, manual-focus cameras, and bulky lighting. Taking good photos of small moving objects with that sort of equipment is tough. I've been reading through some old (30's - 50's) issues of National Geographic and it seems like live insect photography, especially outside, was a novelty for a long time.
Personally I don't like to kill bugs (except houseflies) and haven't ever killed one for a photo. But some of the objections take it way too far. Insects would overrun the planet in a day or two if something didn't kill a bunch of them, so killing a few to make attractive and/or educational photos seems like a pretty minor offense against nature. After all, how many bugs die a useless death every day smashed against your headlights, flattened under your bike tires, or crushed underfoot?