NOW THIS IS A SCARY HALLOWEEN STORY...
Latrodectus hespenus

The knot-hole in a ficus tree near our house is home to a black widow spider. The skeletal remains of at least two male spiders litter the floor around little cottony balls of what I presume are bags of eggs. The female black widow kills and eats the male after they mate. There is evidence in their lair that there has been a lot of mating going on around here. Apparently she sucks the insides out of the male after she has her way with him... an altogether grim cautionary tale. I read that male black widows (Is male-widow a contradiction in terms?) and juveniles are harmless to humans. But the female! Wow! Her venom is 15 times as toxic as the venom of the prairie rattlesnake. She is considered the most venomous spider in North America, but her bite seldom causes death to humans because she injects a very small amount of poison when she bites... small consolation to the males she kills and eats.