I inadvertently upset my seven-year-old nephew once by feeding a ladybug to a black widow spider. Ladybugs, he'd been told, were "good bugs." I tried to comfort him by pointing out that the ladybug didn't care about the human race, or about the good of the world, and was probably only eating aphids because it was hungry, not from any moral imperative. Furthermore, I said, the widow has at least as good a claim to sparing us the annoyances of a wide range of insects. My son, four at the time, assured him that one of the little orange creeps had bitten him and that he harbored a grudge against the entire race of them. In any event, the ladybug did some good that day by serving as a protein shake.
I wrote about ladybugs (a.k.a. lady beetles, ladybird beetles) in Deadly Kingdom.
I wrote about black widow spiders (Latrodectus spp.) in The Red Hourglass and Deadly Kingdom.