Black widows spin their webs in crevices between rocks, under logs or
overhanging banks, in abandoned rodent holes, and in rock and wood
piles. Indoors they are most frequently encountered in dark corners of
garages, basements, and stables.
[Illustration: _Underside of black widow spider showing
characteristic red “hourglass” mark on the abdomen by which this
species may be recognized._]
A favorite and especially dangerous location in which a black widow
establishes her home is beneath the seat of a pit toilet. Such a
location is ideal for the spider because it is dark, is not usually
disturbed, and insects, especially flies, upon which the spiders feed,
are abundant. Humans using the toilet, unaware of the presence of the
spider, arouse her by breaking or agitating her web, and offer
especially tender and susceptible portions of their anatomies for her
bite.
Pit toilets in warm climates should always be built with hinged seats
which should be raised and inspected frequently. As a further
precaution, the underside of the seats should be treated with creosote,
an effective repellent.
Although the majority of people now recognize the black widow, some do
not, hence they kill all dark-colored spiders on general principles.
This is neither necessary nor desirable.
The female black widow is a medium-sized, glossy black, solitary spider
with a globular abdomen spectacularly marked on the underside with a
bright red spot roughly the shape of an hourglass. The normal position
of the spider is hanging upside down in her web so that the “hourglass”
is plainly visible if she is below the level of the eye. Her overall
length is 1 to 1¼ inches.
The males are much smaller and, like the immature females, are grey in
color and variously striped and spotted.
Adult females spin egg cocoons during the warm season; each cocoon
contains approximately 300 to 500 eggs which hatch in about 30 days. As
many as nine broods per year have been recorded. The young grow fast but
do not mature until the following spring or summer.