Not even sure I should mention this here (might be classified as cruelty to some) , but one way to make it easier to shoot cold blooded creatures (including insects, I believe), is to put them in a fridge for a while to cool them down. Makes them less active, and easier to shoot. But if you do, don't leave them in for too long, as you don't want spider popsicles, and remember you don't have too much time to shoot as they warm up.