Widow spiders

Information just in time for Halloween where spider webs and spooky spiders are a common sight.

There are four species of widow spiders found in Texas, with the best known being the black widow.  Coloration can vary, but they are typically jet black with two reddish-orange triangles on the underside of the abdomen, forming an hourglass shape.  The triangles sometimes do not touch each other creating a broken hourglass shape.  Males and juveniles are smaller and often are more colorful, with bright markings on their sides or back.

Females lay eggs in an oval sac which can hold from 25 to over 900 eggs.  Depending on temperature and time of year, eggs usually hatch after about 20 days.  Spiderlings stay near the egg sac for several days where they can be seen consuming their brothers and sisters.  The survivors throw a thread of silk to the wind and are carried off in a process called “ballooning”.  They eventually locate a sheltered spot where they build a loosely woven web and remain for the rest of their lives.  As time progresses, the spiders build larger webs to capture larger prey.  Males eventually leave their webs to find females for mating.  In natural settings, most females do not eat males after mating.

Widow spiders do not like being in the open.  They can often be found outside in protected areas such as rainspouts, shrubbery, firewood piles or unused BBQ pits.  It is also possible to find them in garages, cellars, attics, furniture or electric or water meter boxes.  Widows are shy creatures and often people are bitten when a web is accidentally disturbed.

The bite of a black widow sometimes is not noticed, but when it is, it often feels like a pin prick.  The bite location will have two red marks surrounded by redness and swelling.  The bite reaction is systemic and intense pain usually occurs within 1-3 hours and continues for up to 48 hours.  Other symptoms include tremors, nausea, vomiting, leg cramps, abdominal pain, profuse perspiration and rise in blood pressure.  It is also possible for breathing difficulties and unconsciousness to occur.  If bitten by a black widow, immediately seek medical attention.

When working around the house or in the yard, it is best to wear leather gloves to avoid being bitten by venomous arthropods.