Well, this is a weird one. Another movie I saw as part of last October's 31 horror movies, I watched this one with some friends.
This movie is about the Merrye family and the rare genetic disorder among them that makes them regress to cannibalistic cave dwelling predators the older they get. Lon Chaney Jr. is Bruno, the caretaker for the three "children" who use their sexuality and seeming innocence to their advantage. One is the Spider Baby of the title as she keeps a nest of ropes over her window to catch anyone climbing in and then she stabs them with butcher knives that she calls stingers. We see a poor delivery man fall to this fate early on. Distant relatives arrive at the house to see about inheriting the property and Bruno is forced to leave the kids unsupervised in a house full of normals. Some bad things, like rape and murder, then happen.
The subject matter is pretty bold and risque for the 1960s. I was surprised with how much this movie got away with. It is hard to find a likable character. The visiting Uncle, Peter, is very patient and kind with the "kids" but after seeing how they behave, Peter may just be a moron. Even the normal people in the house are depraved in various ways so there isn't much empathy when one gets killed. Also, stay for Sid Haig's wild performance as the eldest son of the Merrye clan.
All in all, this is a fun (if sick) exploitation film that is never not entertaining. Certainly not an essential watch but I don't think you'll regret it if you stumble upon it.