When a weapon comes at a high cost, it makes sense to use it judiciously. “Dry” bites and stings have been reported in various snakes, spiders, and insects, suggesting that they have a choice of whether or not to use venom at all. They also seem to be able to control just how much venom to deploy when they use it. Snakes and spiders have been known to “meter” their venom while hunting, using varying amounts depending on the type of prey and how much it struggles.
The secret strategy behind the black widow’s bite