Latrodectus is a genus of
spider, in the family Theridiidae,
that contains 31 recognized
species. The common name
widow spiders is sometimes
applied to members of the genus
due to the habit of the female
of eating the male after mating,
although sometimes the males of
some species are not eaten
after mating, and can go on to
fertilize other females.[1] The
black widow spiders are
perhaps the best-known
members of the genus. The
injection of neurotoxic venom
latrotoxin from these species is
a comparatively dangerous
spider bite, resulting in the
condition latrodectism, named for
the genus. The female black
widow's bite is particularly
harmful to humans because of its
unusually large venom glands.
Latrodectus bites rarely kill
human beings.
Description
Not all adult female black widows
exhibit the red hourglass on
their abdomen—some may have a
pair of red spots or have no
marking at all, but any markings
that are present are bright red.
Adult male black widows are a
quarter the size of the female,
and are usually gray or brown
rather than black and red; while
they may sometimes have an
hourglass marking on their
abdomen, it is usually yellow or
white, not red. The bite of a
male black widow is not
considered dangerous to
humans; it is the bite of the
adult female black widow from
her much larger venom sacs that
has given this spider its
dangerous reputation. While
there is great variation in
specifics by species and by
gender, any spider exhibiting a
red hourglass on the abdomen
and having a shiny black body is
an adult female black widow.
Spiders of the genus Steatoda
(also of the Theridiidae family)
are often mistaken for widow
spiders, and are known as "false
widow spiders"; they are
significantly less harmful to
humans.
In comm.on with other members
of theTheridiidae family, the
widow spiders construct a web
of irregular, tangled, sticky
silken fibers. 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. If the spider
perceives a threat, it will quickly
let itself down to the ground on
a safety line of silk. As 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. While there are
some more aggressive species,
most are not; many injuries to
humans are due to defensive
bites delivered when a spider
gets unintentionally squeezed or
pinched. Some bites are thought
to result from a spider mistaking
a finger thrust into its web for
its normal prey[citation needed],
or in cases where a female is
protecting an egg sac, but
ordinarily intrusion by any large
creature will cause these spiders
to flee.
spider, in the family Theridiidae,
that contains 31 recognized
species. The common name
widow spiders is sometimes
applied to members of the genus
due to the habit of the female
of eating the male after mating,
although sometimes the males of
some species are not eaten
after mating, and can go on to
fertilize other females.[1] The
black widow spiders are
perhaps the best-known
members of the genus. The
injection of neurotoxic venom
latrotoxin from these species is
a comparatively dangerous
spider bite, resulting in the
condition latrodectism, named for
the genus. The female black
widow's bite is particularly
harmful to humans because of its
unusually large venom glands.
Latrodectus bites rarely kill
human beings.
Description
Not all adult female black widows
exhibit the red hourglass on
their abdomen—some may have a
pair of red spots or have no
marking at all, but any markings
that are present are bright red.
Adult male black widows are a
quarter the size of the female,
and are usually gray or brown
rather than black and red; while
they may sometimes have an
hourglass marking on their
abdomen, it is usually yellow or
white, not red. The bite of a
male black widow is not
considered dangerous to
humans; it is the bite of the
adult female black widow from
her much larger venom sacs that
has given this spider its
dangerous reputation. While
there is great variation in
specifics by species and by
gender, any spider exhibiting a
red hourglass on the abdomen
and having a shiny black body is
an adult female black widow.
Spiders of the genus Steatoda
(also of the Theridiidae family)
are often mistaken for widow
spiders, and are known as "false
widow spiders"; they are
significantly less harmful to
humans.
In comm.on with other members
of theTheridiidae family, the
widow spiders construct a web
of irregular, tangled, sticky
silken fibers. 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. If the spider
perceives a threat, it will quickly
let itself down to the ground on
a safety line of silk. As 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. While there are
some more aggressive species,
most are not; many injuries to
humans are due to defensive
bites delivered when a spider
gets unintentionally squeezed or
pinched. Some bites are thought
to result from a spider mistaking
a finger thrust into its web for
its normal prey[citation needed],
or in cases where a female is
protecting an egg sac, but
ordinarily intrusion by any large
creature will cause these spiders
to flee.
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