Other spider venom is necrotic and causes damage to the tissues surrounding the site of the bite. The recluse spiders have necrotic venom. The damage usually results in skin blisters, ulcers and blackening of the local tissues. No, probably not. Of course, insects are seriously affected by the venom since insects are the staple of most spiders' diet.
Spiders inject venom into the body of a captured insect to paralyze it.
Cats are very susceptible to black widow venom as are horses but dogs are relatively resistant, and sheep and rabbits are apparently immune. While there are only a few spiders in the United States that are really dangerous to humans, there are significant numbers around the world. The black widow and recluse spiders have very toxic venom that can be life threatening to humans. Pigeon spiders of West Africa give very painful bites. There are four main methods that spiders use to capture prey.