WARNING! Poisonous spiders are in my house! If you are afraid of spiders, DO NOT WATCH this video.
If you don’t yet know the story, I started finding black widows in my house, and I have plenty of other videos talking about that. In this video I show the results of following a comment I received about using a praying mantis to get rid of the spiders.
Female widow spiders are typically dark brown or a shiny black in color when they are full grown, usually exhibiting a red or orange hourglass on the ventral surface (underside) of the abdomen; some may have a pair of red spots or have no marking at all. The male widow spiders often exhibit various red or red and white markings on the dorsal surface (upper side) of the abdomen, ranging from a single stripe to bars or spots. Females of a few species are paler brown and some have no bright markings. The bodies of black widow spiders range from 3 to 10 mm in size, some females can measure 13 mm in their body length.
The prevalence of sexual cannibalism, a behavior in which the female eats the male after mating, has inspired the common name “widow spiders”. This behavior may promote the survival odds of the offspring; however, females of some species only rarely show this behavior, and much of the documented evidence for sexual cannibalism has been observed in laboratory cages where the males could not escape. Male black widow spiders tend to select their mates by determining if the female has eaten already to avoid being eaten themselves. They are able to tell if the female has fed by sensing chemicals in the web. 
Like other members of the family Theridiidae, widow spiders construct a web of irregular, tangled, sticky silken fibers. Black widow spiders prefer to nest near the ground in dark and undisturbed areas, usually in small holes produced by animals, or around construction openings or wood piles. Indoor nests are in dark, undisturbed places as well such as under desks or furniture or in a basement.The spider very frequently hangs upside down near the center of its web and waits for insects to blunder in and get stuck. Then, before the insect can extricate itself, the spider rushes over to bite it and wrap it in silk. To feed, it uses its fangs to inject digestive enzymes, liquefying the prey’s internal organs. Their prey consists of small insects such as flies, mosquitoes, grasshoppers, beetles, and caterpillars. If the spider perceives a threat, it quickly lets itself down to the ground on a safety line of silk. As with other web-weavers, these spiders have very poor eyesight and depend on vibrations reaching them through their webs to find trapped prey or warn them of larger threats. When a widow spider is trapped, it is unlikely to bite, preferring to play dead or flick silk at the potential threat; bites are the result of continual harassment. While some species are more aggressive, most are not; many injuries to humans are due to defensive bites delivered when a spider gets unintentionally squeezed or pinched.
The ultimate tensile strength and other physical properties of Latrodectus hesperus (western black widow) silk were found to be similar to the properties of silk from orb-weaving spiders that had been tested in other studies. The tensile strength for the three kinds of silk measured in the Blackledge study was about 1000 MPa. The ultimate strength reported in a previous study for Nephila edulis was 1290 ± 160 MPa. The tensile strength of spider silk is comparable to that of steel wire of the same thickness. However, as the density of steel is about six times that of silk, silk is correspondingly stronger than steel wire of the same weight.