A neurotoxin strong enough to cause days of crippling pain is metabolically expensive to produce. So, for that matter, is spider silk. And so, the researchers concluded, black widows aren’t the wanton killers that many fear. More pussycat than raptors, they are strategic, not aggressive. Think "Meow. Pffffft! Wham!" and not "Zoom. Screech. You're dead."
It sounds like a graduate student nightmare: the job of provoking attacks by black widow spiders. But in three experiments conducted at Loma Linda University, grad students in William H. Hayes’ lab of the School of Public Health used gelatin "fingers" to poke and pinch black widows in an attempt to determine how promiscuously they dispense their venom. As described in an article in press at Animal Behavior, the answer is "not terribly.” When poked, the spiders tended to move away from the finger. When poked repeatedly, they flicked silk at it. When pinched on the leg, they sometimes bit, though often the bites were “dry,” containing no venom. When pinched on the body, however, payback was immediate and awful.