Some do occur in southern Missouri, but they are not very abundant. Only two Missouri species, the black widow and the brown recluse, are capable of causing a serious condition by injection of venom. Others may cause very minor irritation. Most spider bites occur without the victim being aware that it is happening. The female black widow is jet black with a red hourglass-shaped marking usually present on the underside of the abdomen.
Some specimens have a few other small red spots, particularly on the top surface of the abdomen.
The males are much smaller than the females and usually have yellow and red bands and spots over the body, as do the immature black widows. Only the females can inflict a poisonous bite. The black widow lives in undisturbed locations such as trash, litter and under boards and rocks. Outbuildings may be infested as well as crawl spaces, cellars and basements. The spider remains in the irregular web constructed in space between objects.