There are two species of widow spiders
in California, the western black widow
and the brown widow. Both are in the
genus Latrodectus and are characterized
by a similar body shape, reclusive habit,
and haphazardly constructed cobwebs.
The western black widow spider—a
native species—is widespread and is
the spider posing the greatest threat to
humans in the Western United States. It
is well known in many localities, and
nonprofessionals can identify it easily.
In the first decade of the 21st century,
the non-native brown widow became
established in Southern California, and
although it isn’t nearly as dangerous as
the black widow, it causes alarm because
of
its
potentially
deadly
relative.