House spider cannibalism

These two house spiders (Parasteatoda tepidariorum) either just mated, or were about to, as far as the male, in the lower left was concerned. Unfortunately for him, sexual cannibalism is common in spiders, meaning a female will often eat the male who just fertilized her. Praying mantises are infamous for this, but it’s really the arachnids who make a habit of it. Males of different species have different strategies to avoid this, whether by bringing a large piece of food, waiting until the female has recently molted, or just by being quick and sneaky. Some scorpion males will even sting the female to subdue her until he’s safely away. But other arachnid males will let themselves be captured by the female, or simply don’t have good luck in escaping freely.

Interestingly, these two are pretty close in size. The likelihood of a male being eaten by the female is pretty much proportional to the size difference between the two, since females are usually much larger. So it seems quite possible that this is a species where the male lets the female eat him.

If you look carefully, the male has some webbing wrapped around him, and his legs are curled in the classic spider ‘death pose’; I stuck around for a few minutes and she immediately started biting at a joint in one of the legs, but I had to leave before I could see if she was just subduing him with venom or was actually starting to eat. He’s missing his front left leg, and on a 100% crop a drop of clear liquid is visible in it; I wonder if the digestive enzymes spiders inject into their prey have already taken effect, but I have no idea if it would be visible in a leg wound like that.