What's Bugging You? Black Widow Spider


COMMON NAME: Black Widow Spider

SCIENTIFIC NAME: Latrodectus species

ADULTS - Female: glossy black (or sometimes brown) with the characteristic red "hour-glass" shape on the underside of her abdomen. She can reach a half inch long with long, thin legs up to two times the body length. The abdomen is large and bulbous, rather teardrop in shape when viewed from the side and ending with a pointed "spinneret". She will usually be found hanging upside down in her web with the red hourglass clearly visible. The female will seldom leave the web.

Male: Somewhat smaller than the female, he has a slightly more elongate body shape and different coloration. He may be black or dark brown with small red dots on the sides of the abdomen or he may be a mottled brown/gray/orange color. Because of the differences, he is often not recognized at all. At maturity, he will leave his web in search of a mate.

Eggs: The eggs can be found in a tan sac in the web of the female. She may produce up to nine egg sacs during the year and each sac may contain up to 500 eggs.

Young: The Black Widow Spiders are like miniature adults with the mottled brown/gray/white coloration and the characteristic long legs and bulbous abdomen shape. They may appear to be spotted or striped and will get darker in color as they mature and molt.

LIFE CYCLE: The female lays her eggs in a web sac attached to her web. She can be VERY AGGRESSIVE in her defense of her eggs! After the spiderlings hatch, those that survive set up housekeeping in their own webs. Outside, the young are often dispersed by the wind, while inside the large numbers of them may be found in the same area. As they mature and grow larger, the mottled coloration will darken, finally becoming glossy black or brown and acquiring the characteristic red markings of the adult. Final maturity usually happens during the summer causing the "sudden appearance" of Black Widows from a up-to-now unnoticed population of mottled immature spiders.

TIME OF YEAR: Black Widow Spiders are with us the year 'round. Populations will peak during the warm months with is when the last year's brood will mature and new eggs will be laid and hatched. Due to our mild winters, some will even survive the "cold" season outside but they will usually seek more protected places to spin their webs and may even try to move indoors.

WHAT TO LOOK FOR: Look for webs that look like they were spun by a very drunk spider! The Black Widow typically spins a very messy-looking web that bears little resemblance to the stereotypical neat and symmetrical web of most spiders. The web will be very string and can be rather large in proportion to the arachnid that created it. The spider itself may be easily seen hanging upside down from the web, or more likely, s/he may be hiding at the outside edge of the webbing or even in a dark crevice or corner nearby.

Be especially watchful in storage buildings, attics, crawl spaces, etc. where humans rarely go and the food (insects, etc.) population is plentiful. In the house, they will often be found in the garage, the back of the pantry or any comer that is out of the traffic pattern. Be extra careful when unpacking seasonal clothing or equipment. In the garden, they will often make their webs between the interior branches of shrubs and trees. Unused pots, netting or tools should be carefully examined instead of just grabbing and going.

If you engage in a lot of outdoor sports such as camping, look closely before using an outdoor latrine. Black Widows are commonly found in the comers and under the seats in these buildings and an encounter can be very dangerous (not to mention extremely painful and embarrassing!).

PROBLEMS AND DAMAGE: On the plus side, most spiders are very good to have around the home and garden to help control insect pests. On the negative side, the Black Widow Spider is one of the few spiders in the U.S. that are considered dangerous and possibly lethal to humans.

CULTURAL CONTROLS: If the spiders are in an area where they pose no danger to humans or companion animals you can probably just leave them as they are and enjoy the fact that they are eating their weight in insect pests on a regular basis. If they do pose a threat or you simply can't live with them, then probably the best way to get rid of them is by frequent and thorough cleaning away of their webs and the destruction of the spider and any egg cases.

MECHANICAL CONTROLS: Simply using a broom to squash them is a time-honored and effective method of spider control. Just about any solid or semi-solid weapon can be used as long as you can quickly and effectively maneuver it (these critters move FAST) while keeping a safe distance.

NATURAL CONTROLS: The spiders themselves are probably their own worst enemy. Few of the young survive to maturity and the males generally get the worst of the deal after the mating ceremony is completed. As usual, trying to attract birds and friendly toads and lizards to your garden can't hurt

BIOLOGICAL INSECTICIDES: Black Widows are very hardy creatures and the larger they get the harder they are to kill. You can try the insecticides used on hard-shelled beetles, but don't be surprised if repeated doses are needed or they don't work at all on the big ones.

CHEMICAL CONTROLS: Please consult the Agricultural Extension Agent or a Master Gardener Volunteer for current recommendations. Phone 458-1104 in Sierra Vista or 384-3594 in Willcox. Personally, I have had success with the formulations meant for use on wasp nests. Whatever you use, FOLLOW LABEL DIRECTIONS EXACTLY and take the necessary precautions to protect yourself, other humans, non-target animals and the environment.

HOW TO AVOID A BLACK WIDOW SPIDER BITE: The first, last and always rule for avoiding bites or stings from venomous creatures is: NEVER PUT YOUR HANDS, FEET OR ANY OTHER PART OF YOUR ANATOMY WHERE YOUREYES HAVE NOT BEEN YET!!I! Always look before reaching into comers, boxes, woodpiles or stacks of pots or other supplies. Black Widows like dry, dark, undisturbed areas and can set up housekeeping anywhere where two or more surfaces are close enough to attach webbing to. Rule number two: Leave the creature alone! Spiders, like almost all other animals, will avoid humans and will run away if any avenue of escape is left open to it. Don't allow children or anyone else to poke sticks into the web or otherwise annoy the spider. The animal may get angry or scared enough to bite. This is especially true if there is an egg case present!

CURRENT MEDICAL INFORMATION: The bite of the Black Widow is usually painful and there will be a puncture-type wound. The venom appears to affect the nervous system and the entire body can become affected. There may be dizziness, headache and muscle cramping and perhaps some nausea and vomiting. The victim should be kept as calm as possible and an ice pack may be applied to the bite wound to reduce the pain and swelling. (Be sure to wrap the ice in a cloth to prevent cold damage to the skin.) You may also use an over- the-counter pain reliever such as asprin, acetaminophen or ibuprofen. At this stage it is suggested that you call the Poison Control Center (l-800-222-1222) or your local hospital for further information. If the muscle cramping becomes severe or the victim experiences difficulty in breathing, it is highly suggested that you go to the emergency room of the nearest medical facility in case further treatment is necessary. This is especially important in the case of small children, elders or anyone else who may be at extra risk because of small size, disability or prior illness. This is of special importance for anyone with high blood pressure or cardiac problems. Although most adults in good health can expect to recover from a Black Widow bite, it is wise to not take chances. The practice of applying a constricting band above the bite is no longer recommended because of the possible damage due to decreased blood flow. After arrival at the hospital the patient will be observed and treated according to the effects of the venom on that individual. This may mean simple observation, medication for the pain or in rare cases, an antivenin may be given.


T.J. Martin
October, 1993