It is important to remember that the female black widow has a very shiny abdomen that is black. It is roundish and there is an hourglass pattern on the bottom that is normally red but can be orange or even yellow. When you observe the size of the female black widow, it will rarely have a body larger than the size of a penny. The mature northern black widow female, a sub-species of this type of spider, is sleek, black and has red spots in a row on the very top of its abdomen, with the characteristic hourglass shape on its lower belly. The most distinctive feature of the brown recluse, which is a brown spider, is the violin-like pattern on its head. This gives the recluse its nickname of "fiddleback," as the fiddle is easily viewed by even a casual observation.
The cobweb constructed by the black widow is sturdy and usually measures about a foot across. The female will spend her day hiding on a side of this web, waiting for insects to become entangled. The black widow will weave its web in buildings such as old sheds, garages, barns and abandoned buildings. When encountered outside, the black widow may be behind a woodpile, in a stump or in an unused animal burrow. The brown recluses will inhabit similar areas but are also likely to frequent cluttered homes, hiding themselves in the darkest places they can find. If they manage to get into a closet or a drawer, the brown recluses can wind up inside clothing, which creates problems for anyone who eventually tries to wear the garment.
While the black widow's venom is 15 times more powerful than that of a prairie rattlesnake, the spider often cannot inject a large amount into the victim when it bites. For this reason, the death rate from black widow bites is less than 1 percent in the U.S. However, the bite is still serious, precipitating such symptoms as pain, swelling, redness, abdominal discomfort, headache and sweating. More dangerous signs of this spider's bite include high blood pressure, chest pains, nausea, vomiting and respiratory distress. The brown recluse's bite can result in the same set of symptoms as the black widow if enough of its venom is injected into the body. While most of these bites will heal quickly and few symptoms will be felt, sometimes the area becomes necrotic after a period of time. When this does happen, a white blister will initially develop and the area will change color to red and then bluish-gray to white. In the most severe instances, the bite will turn into a deep and painful lesion that can take months to properly heal. When fatalities from the brown recluse do occur, they are usually in small children and the elderly.