Spider Control Services

In the mature brown recluse spider as well as some other species of recluse spiders, the dark violin marking is well defined, with the neck of the violin pointing toward the bulbous abdomen.

The abdomen is uniformly colored, although the coloration can range from light tan to dark brown, and is covered with numerous fine hairs that provide a velvety appearance. The long, thin, brown legs also are covered with fine hairs, but not spines.

Adult brown recluse spiders have a leg span about the size of a quarter. Their body is about 3/8 inches long and about 3/16 inches wide. Males are slightly smaller in body length than females, but males have proportionally longer legs. Both sexes are venomous.

The immature stages closely resemble the adults except for size and a slightly lighter color. Whereas most spiders have eight eyes, recluse spiders have six eyes that are arranged in pairs in a semicircle on the forepart of the cephalothorax (see close-up view).

A 10X hand lens or microscope is needed to see this diagnostic feature. To determine the exact species of Loxosceles, the spider's genitalia needs to be examined under a high-power microscope. This requires the skills of a spider expert.

Egg-laying primarily occurs from May through July. The female lays about 50 eggs that are encased in an off-white silken sac that is about 2/3-inch diameter.

Each female may produce several egg sacs over a period of several months. Spiderlings emerge from the egg sac in about a month or less. Their development is slow and is influenced by weather conditions and food availability.

It takes an average of one year to reach the adult stage from the time of egg deposit. Adult brown recluse spiders often live about one to two years. They can survive long periods of time (about 6 months) without food or water.

The brown recluse spider spins a loose, irregular web of very sticky, off-white to grayish threads. This web serves as the spider's daytime retreat, and it often is constructed in an undisturbed corner. This spider roams at night searching for insect prey.

Recent research at the University of Kansas indicates that the brown recluse spider is largely a scavenger, preferring dead insects. Mature males also roam in search of females.

Brown recluse spiders generally occupy dark, undisturbed sites, and they can occur indoors or outdoors. In favorable habitats, their populations are usually dense. They thrive in human-altered environments. Indoors, they may be found in attics, basements, crawl spaces, cellars, closets, and ductwork or registers.

They may seek shelter in storage boxes, shoes, clothing, folded linens, and behind furniture. They also may be found in outbuildings such as barns, storage sheds, and garages. Outdoors, brown recluse spiders may be found underneath logs, loose stones in rock piles, and stacks of lumber.

The brown recluse spider is not aggressive, and it normally bites only when crushed, handled, or disturbed. Some people have been bitten in bed after inadvertently rolling over onto the spider.

Others have been bitten after accidentally touching the spider when cleaning storage areas. Some bites occur when people put on seldom used clothing or shoes inhabited by a brown recluse.

The physical reaction to a brown recluse spider bite depends on the amount of venom injected and an individual's sensitivity to it.

Some people are unaffected by a bite, whereas others experience immediate or delayed effects as the venom kills the tissues (necrosis) at the site of the bite. Many brown recluse bites cause just a little red mark that heals without event. The vast majority of brown recluse bites heal without severe scarring (http://spiders.ucr.edu/avoidbites.html).

Initially, the bite may feel like a pinprick or go unnoticed. Some may not be aware of the bite for 2 to 8 hours. Others feel a stinging sensation followed by intense pain. Infrequently, some victims experience general systemic reactions that may include restlessness, generalized itching, fever, chills, nausea, vomiting, or shock.

A small white blister usually initially rises at the bite site surrounded by a swollen area. The affected area enlarges and becomes red, and the tissue is hard to touch for some time. The lesion from a brown recluse spider bite is a dry, blue-gray or blue-white, irregular sinking patch with ragged edges and surrounding redness--termed the "red, white, and blue sign."

The lesion usually is 1½ inches by 2¾ inches or smaller.

The bite of the brown recluse spider can result in a painful, deep wound that takes a long time to heal. Fatalities are extremely rare, but bites are most dangerous to young children, the elderly, and those in poor physical condition.

When there is a severe reaction to the bite, the site can erupt into a "volcano lesion" (a hole in the flesh due to damaged, gangrenous tissue). The open wound may range from the size of an adult's thumbnail to the span of a hand.

The dead tissue gradually sloughs away, exposing underlying tissues. The sunken, ulcerating sore may heal slowly up to 6 to 8 weeks. Full recovery may take several months and scarring may remain.

It is difficult for a physician to accurately diagnose a "brown recluse bite" based simply on wound characteristics. It is absolutely necessary to have the spider for a positive identification.

Necrotic wounds can result from a variety of agents such as bacteria (Staphylococcus, "flesh-eating" Streptococcus, etc.), viruses, fungi, and arthropods (non-recluse spiders, centipedes, mites, ticks, wasps, bedbugs, kissing bugs, biting flies, etc.).

Necrotic conditions also can be caused by vascular and lymphatic disorders, drug reactions, underlying diseases states, and a variety of other agents. Misdiagnosis of lesions as brown recluse bites can delay appropriate care.

If bitten, remain calm, and immediately seek medical attention (contact your physician, hospital, and/or poison control center). Apply an ice pack directly to the bite area to relieve swelling and pain.

Collect the spider (even a mangled specimen has diagnostic value), if possible, for positive identification by a spider expert. A plastic bag, small jar, or pill vial is useful and no preservative is necessary, but rubbing alcohol helps to preserve the spider.

An effective commercial antivenin is not available. The surgical removal of tissue was once the standard procedure, but now this is thought to slow down wound healing. Some physicians administer high doses of cortisone-type hormones to combat hemolysis and other systemic complications.

Treatment with oral dapsone (an antibiotic used mainly for leprosy) has been suggested to reduce the degree of tissue damage. However, an effective therapy has not yet been found in controlled studies.

Control of indoor infestations of the brown recluse spider can take a long time (6 months or more) and can be difficult because humans have a very low tolerance for this pest, it tends to be widely dispersed within infested buildings, and it seeks secluded sites.

Control of spiders, including the brown recluse, is best achieved by following an integrated pest management (IPM) approach. IPM involves using multiple approaches such as preventive measures, exclusion, sanitation, trapping, and chemical treatment when necessary.

• Shake out clothing and shoes before getting dressed. 
• Inspect bedding and towels before use. 
• Wear gloves when handling firewood, lumber, and rocks (be sure to inspect the gloves for spiders before putting them on).
• Remove bedskirts and storage boxes from underneath beds. Move the bed away from the wall.
• Exercise care when handling cardboard boxes (recluse spiders often are found in the space under folded cardboard flaps).
• Exclusion
• Install tight-fitting screens on windows and doors; also install door sweeps.
• Seal or caulk cracks and crevices where spiders can enter the house.
• Install yellow or sodium vapor light bulbs outdoors since these attract fewer insects for spiders to feed upon.
• Tape the edges of cardboard boxes to prevent spider entry.
• Use plastic bags (sealed) to store loose items in the garage, basement, and attic.

• Remove trash, old boxes, old clothing, wood piles, rock piles, and other unwanted items.
• Eliminate clutter in closets, basements, attics, garages, and outbuildings.
• Do not stack wood against the house. 
• Clean up dead insects that the brown recluse spider can feed on.

• Use sticky traps or glueboards to capture spiders. 
• Dust and vacuum thoroughly to remove spiders, webs, and egg sacs (dispose of the vacuum bag in a container outdoors).
• Use a rolled up newspaper or fly swatter to kill individual spiders.

The female Black Widow is shiny black, usually with a reddish hourglass shape on the underside of her spherical abdomen. Her body is about 1.5 inches long. Adult males are harmless, about half the female's size, with smaller bodies, longer legs and usually have yellow and red bands and spots over the back as do the immature stages.



Newly hatched spiderlings are predominately white or yellowish-white, gradually acquiring more black and varying amounts of red and white with each molt. Juveniles of both sexes resemble the male and are harmless.

Curious Facts

• Black Widow is considered the most venomous spider in North America.
• The venom of the black widow spider is 15 times as toxic as the venom of the prairie rattlesnake.
• Black Widow spiders are not usually deadly, especially to adults, because they inject only a small amount of venom.
• Only the female Black Widow is venomous; males and juveniles are harmless.
• The female Black Widow hangs belly upward and rarely leaves the web.
• The Black Widow is also called the "hourglass" or "shoe-button" spider.
• More than 35,000 spider species of spiders occur in the world. Of these, about 3,400 species in 64 families are found in North America.
  

Vital Stats

• Weight: 1 gram
• Length: 1-1.5"
• Span: 1-3"
• Sexual Maturity: 70-90 days.
• Mating Season: Spring
• Incubation: 14-30 days
• No. of Eggs: 250-700/sac
• Birth Interval: 4 to 9 egg sacs/summer
• Lifespan: up to 3 years
• Typical diet: insects

Behavior

Both Western and Eastern Black Widows spin webs that lack shape and form. Their webs are erratic in appearance, and the silk is stronger than almost all other arachnids. The black widow spider is shy and nocturnal in habit, usually staying hidden in her web., hanging belly upward. Although not aggressive, she may rush out and bite when her web is disturbed or when accidentally trapped in clothing or shoes.

Habitat

On the underside of ledges, rocks, plants and debris, wherever a web can be strung. Cold weather and drought may drive these spiders into buildings.

Food and Hunting

Like most arachnids, the Black Widow preys on insects. Prey caught in the web include a variety of insects (cockroaches and beetles) and other arthropods. After ensnaring its prey in the web, the Black Widow makes small punctures in the victim's body and sucks out the liquid contents. The Black Widow is preyed upon by Mud-Dauber wasps.

Breeding

Adult male Black Widows wander in search of females but do not feed or bite. Females may occasionally kill and eat a male after mating but this is more the exception than the rule.

The female then lays several batches, containing up to 750 eggs each, in one summer. The egg case, about 1/2 inch in diameter, is suspended in the web. It is white to tan in color and has a paper-like texture. There may be 4 to 9 egg sacs produced during a summer. Normally, only 1 to 12 young survive after the egg incubation period of 14 to 30 days due to cannibalism.



The young Black Widows are colored orange and white when they emerge 1 to 4 weeks later. The female Black Widow may live for more than a year and a half. Growth requires 2 to 4 months, depending on availability of prey during which the females molt 6 to 8 times and the males 3 to 6 times. Females mature about 90 days after egg sac emergence and live another 6 months to a year. days longer. Males mature in about 70 days after emergence and live only another month or two.

Caution - Venomous!

The venom of the black widow spider is 15 times as toxic as the venom of the Prairie Rattlesnake. But only a minute amount of the toxin is injected with a single bite by the spider, so they are rarely fatal. However, the relatively large amount of injected rattlesnake venom results in about 15 to 25 percent mortality among those bitten.

The bite itself is often not painful and may go unnoticed. But the poison injected by the the Black Widow bite can cause abdominal pain similar to appendicitis as well as pain to muscles or the soles of the feet. Other symptoms include alternating salivation and dry-mouth, paralysis of the diaphragm, profuse sweating and swollen eyelids.

Persons younger than 16 and older than 60, especially those with a heart condition, may require a hospital stay. (Heart and lung failure may result in death.) A physician can give specific antivenin or calcium gluconate to relieve pain. Healthy people recover rapidly in two to five days.

For others, clean the site well with soap and water. Apply a cool compress over the bite location and keep the affected limb elevated to about heart level. Aspirin or Tylenol may be used to relieve minor symptoms. Treatment in a medical facility may be necessary for children less than 5 years old or for adults with severe symptoms. Call the Poison Center for additional information. Poison Centers across the country now have a new national emergency phone number - 1-800-222-1222

Be very careful when working around areas where black widow spiders may be established. Take proper precautions-wear gloves and pay attention to where you are working. The reaction to a Black widow bite can be painful, and the victim should go to the doctor immediately for treatment.

To control the black widow, carefully remove all materials where they might hide. They can be cleaned out of an area simply by knocking down the webs, spiders, and round, tan egg sacs with a stick and crushing them underfoot. Removal or destruction of the egg sacks may help control the population. This spider is resistant to many insecticides.