Black Widow Control

Black widow spiders have been vilified within the world of cinema, causing widespread fear and terror at the sight of one. The female black widow has also been enshrined in human roles to portray a scorned lover that seeks revenge.

The female black widow is widely thought to be the most venomous spider within North America. When compared to rattlesnakes or other venomous creatures, the venom of the female black widow spider remains one of the most toxic around. Though the female black widow is dangerous, males and spiderlings of this species are relatively harmless.

Female black widow spiders are characterized by the large blood red hourglass markings found on their lower abdomen. In some instances, female black widow spiders have been found with an orange-yellow marking instead of blood red. The female black widow abdomen is shiny and black, most often being compared to a marble.

When identifying a female black widow, the hour glass shape is almost certainly a dead giveaway. The eyes of the black widow also take on a unique structure. In black widow species, two horizontal rows of four eyes span the face. The eyes at the ends of each row protrude slightly and have a larger size than the central eyes.

Male black widow spiders take on a slightly different appearance than their female counterparts. While the females are most often a glossy black color, males will typically take on a brown or gray appearance. Both genders, however, still have thick, rounded abdomens that are attached to the thorax. The abdomen in black widow spiders will always match the thorax in color.

The black widow spider is most often found underneath ledges, rock formations, plants and other areas where webs can be constructed. When cold weather arrives black widow spiders will begin seeking shelter inside of structures. This can become an issue when droughts arise as well.

Habits

The black widow spider derived its name from the belief that the female cannibalizes the male after mating. This phenomenon has been observed within laboratory settings but has never been observed in the wild. In most cases, male black widow spiders will continue living in the same web as the female without incident.

The web of a black widow spider lacks form and will often appear like they were built erratically. Though their webs lack the structure and shape commonly seen with orb spiders, black widow spiders produce one of the strongest silks among all other arachnids. The webs created by these spiders are incredibly sticky, which is beneficial for trapping prey.

Like most other spiders, the black widow spider is nocturnal in nature and seeks solitude as often as possible. This species is not inherently aggressive, but will defend her web at all costs when necessary. Black widow spiders are notoriously shy and spend most of their time exposing their abdomen within the web.

Female black widows capture their victims within the silk they produce, wrapping it similar to a cocoon. Once completely covered in silk, prey is neutralized with the injection of venom. Though the prey is immediately available for consumption, often the black widow will save them for later feeding.

It is believed that the red hourglass present on female black widow abdomens was formed as a warning sign to keep potential predators away. The idea is that the red will inform predators that the spider is highly venomous. This, however, is not effective in some animals, such as birds, who perceive color differently.

Life Cycle

Female black widows are capable of storing sperm from their first mating and can produce more than 10 eggs sacs without mating again. Because of these storing habits the female black widow sees no reduction in egg amounts or mortality rates within the eventual spiderlings. This characteristic helps these often solitary spiders thrive.

• Eggs – Black widow females will often lay several groups of eggs with nearly 750 eggs each during the average summer. Once these batches of eggs have been created, she will encase them with silk to create an egg sac. Egg sacs are always placed within the black widow’s web to remain protected.
• Egg Sac – Black widow egg sacs are formed in a tear drop shape that takes on a yellowish hue. Relatively large against other species’ egg sacs, black widow spider egg sacs are large and well defined. Though they tend to have the appearance of cotton balls, the egg sac is durable and hard to rip.
• Spiderlings – Black widow spiderlings emerge from egg sacs one to four weeks are being encased. It is common for only one to a dozen spiderlings to survive longer than a month due to cannibalization by other spiderlings. Most often black widow spiderlings are a white color, or an orange hue, after emerging.
• Adult – After a female molts six to eight times, or a male molts three to six times, the black widow spiderlings will reach adulthood. It is not uncommon for a female black widow spider to survive more than a year and a half under optimal conditions following the 90 days it takes to reach adulthood. Males with typically reach adulthood after about 70 days but only live a maximum of two months more.

Health Threats

The female black widow is considered North America’s most venomous spider, with venom reportedly 15 times stronger than that of a rattlesnake. The most powerful toxins within black widow venom are called latrotoxin, the most potent of which is alpha-latrotoxin. These toxins primarily function to target nervous systems within other insects.

Researchers have discovered that black widow spider venom contains several other toxins that can aid alpha-latrotoxin in its rate of success. Though the venom of a female black widow spider is among the strongest, it isn’t nearly as deadly as other large venomous predators. This is primarily due to the small size of the black widow and the amount of venom it is capable of injecting into a victim when biting.

Generally, humans are only bitten by black widow spiders in the event of accidental contact. When the spider feels threatened it is more likely to attack out of self-preservation. Black widow spiders are passive to humans naturally and often will not go out of their way to attack.

When a human is bitten by a black widow spider, and significant venomization occurs, a syndrome called latrodectism arises. This illness causes symptoms such as sweating, vomiting, muscle tightening and dispersed pain. In most cases, a bite from a black widow spider will only cause localized pain and no other symptoms will form with general treatment. Nearly 75% of all cases involving black widow bites have no venomization or a mild amount that will only cause minor sickness.

In some cases, victims who were unaware of venomization or contact with a black widow spider have been misdiagnosed. The most common misdiagnoses are tetanus or acute abdomen. This often leads to a need for blood values to provide evidence of myocarditis or dehydration from vomiting.

When an individual believes they have been bitten by a black widow spider, it is important to contact a medical professional. Advancements within black widow venom studies have made the likelihood of death almost nonexistent. Though the mortality rate has fallen when dealing with black widow bites, certain medications can be given to ease the symptoms of a black widow bite.

If significant amounts of venom are detected following a bite doctor’s will provide an antivenin. The only known antivenin for the treatment of a black widow venomization is derived from horse serum. This particular antivenin is created by gradually increasing venom injections in a horse, which causes a natural antivenin to be used in human applications.

The current mortality rate for black widow spider bites is often reported anywhere between 5% or the low end at 0.2%. In most cases, victims that have received a bite and developed latrodectism will fully recover with no significant medical problems. Only special complications such as age, immune system functionality and heart problems are present when a death is found.

Prevention

When dealing with black widow spider prevention, the advice is generally not much different than associated with the average spider. Although the black widow is more feared than the average spider, it is a spider nonetheless. These common spider prevention techniques can help keep black widow spiders out of your home.

• Eliminate Hiding Spots – Black widow spiders look for dark, secluded areas to create webs for nesting locations. Clearing debris and food sources that may otherwise entice them to stay can help discourage black spiders from staying in these locations. The removal of items such as resting trash cans and wood piles is encouraged as they are also suitable environments for black widow spiders to flourish.
• Seal Cracks – Often spiders will find their way indoors through cracks and holes that provide access inside. To fill these holes, use caulk to make entry less likely. Venting and chimneys also provide easy access to a wide variety of arachnids and should be covered with mesh insect screens.
• Clear Debris Piles – Vegetation provides an excellent hiding spot around a home for a variety of pests, black widow spiders included. Removing mulch, stones, and leaves near the home will eliminate spots for spiders to hide. Clearing vegetation that connects to the home will eliminate transit lines to a home.
• Maintain Cleanliness – A clean home is less likely to be attractive to pests because food sources will be more scarce. Clutter provides ideal hiding spaces for spiders, as many prefer dark places for shelter. An abundance of cardboard boxes in areas such as a garage or attic can provide endless hiding spots for spiders.
• Remove Webs – Black widow spiders hunt and protect egg sacs from the messy webs they create. Egg sacs, and spider webs they are attached to are easily removed with a vacuum. This can be very effective for removing spiders that are generally not at ground level. Typically, this method of prevention is not effective if large populations of spiders are already present.
• Apply Insecticide – If prone to spider infestations, homeowners may elect to apply insecticide to corners and cracks that may be utilized by spiders. It is important to remember that the insecticide you use must be pet-friendly if you have pets within the home. In general, the most commonly used insecticides against spiders contain pyrethroid in some form.
• Contact an Exterminator – Spider infestations can take their toll on homeowners. In some cases, preventative measure or exterminator intervention may be required. Arrow Exterminators has over 60 years’ experience in providing Oklahoma brown recluse spider control. We understand that spiders are essential to controlling bugs and keeping Oklahoma healthy; however, if you have black widow spiders in your home, you undoubtedly understand the importance of spider control.

Ask the Entomologist

Female black widows killing their mate makes for a good T.V. drama, but is more myth than reality. Fact is the male Black Widow is rarely killed by the female. To top it off, the male even lives longer.