Spiders are beneficial to the ecosystem as natural insects control. Contrary to what most people think, only a few spiders are the bad ones. These spiders produce toxic venom known to cause potentially life-threatening injuries when injected into bitten prey or humans. Animals such as these are referred to as ‘venomous’ not ‘poisonous’ (Note that poisonous animals are animals that cause harm when eaten or ingested). Of the almost 100 species of spiders indigenous to Alabama, only five types pose any deadly threat to human life.
In this article, we’ll take you through the five venomous spiders in Alabama, how to identify them and how dangerous they are to humans.
Black Widow Spider (Latrodectus mactans)
The black widow spider, also called the southern black widow, is a venomous spider native to North America. Widow spiders occasionally eat their males after mating, a gruesome act that gave them their ‘widow’ title. Female black widows are well known for their distinctive shiny black color with a red hourglass-shaped pattern on the underside of their rounded abdomen. Females are markedly larger than males and have long, hollow needle-like chelicerae with which they inject venom. So, it’s the females you need to watch out for.
The black widow spider is highly venomous and is considered one of the most dangerous threats to people in Alabama. Its venom contains a neurotoxin that can cause local symptoms such as pain, swelling, or redness around the bite area, as well as sweating, vomiting, cramping, and nausea. But it is rarely fatal to healthy humans, and most people who are bitten recover quickly without long-term effects.
Northern Black Widow Spider (Latrodectus variolus)
Another widow species, the northern black widow is closely related to the previously described black widow. The characteristic red hourglass marking of widow spiders appears broken in this species, unlike the solid hourglass pattern in the female southern black widow. Male northern black widows are not black but are gray or brown with red spots and four diagonal white bands on each side of the abdomen. These spiders prefer to hide in dark areas, undisturbed woods, stumps, and stone walls, where they can avoid human contact.
A bite from a northern black widow may cause severe discomfort or spread of local redness accompanied by severe pain. If you suspect that this notorious spider has bitten you or anyone you know, It is important to seek urgent medical attention. Despite their fearsome reputation, bites rarely occur because these spiders are shy and would rather flee if threatened. Widow spiders only bite defensively when provoked or if their web is disturbed.
Brown Recluse Spider (Loxosceles reclusa)
Known to be one of the most dangerous spiders in the United States because of its deadly venom, the brown recluse spider occurs throughout Alabama, though more common in the northern regions. They are small spiders, with adults growing to an average length of 0.24 to 0.79 inches. As its name suggests, the body of the brown recluse is light brown with dark brown, white or blackish gray spots. Its cephalothorax is light brown or yellowish-brown with a black line forming a violin-shaped pattern on the dorsal section, pointing towards the abdomen. Unlike other spiders, recluses have six eyes instead of eight, arranged in median (one) and lateral (two) pairs.
A single bite from the brown recluse spider contains a hemotoxic venom that produces symptoms varying from mild to severe, requiring medical treatment. In some cases, intense tissue damage and necrosis (decaying of the tissue due to cell death) occur. But the effect on others may not be more than that of a bee sting. Most fatalities are in children under seven or those with weak immune systems. Brown recluses, from their name, are shy and solitary, and they frequently build their webs in dry and generally undisturbed places. They bite when they feel threatened or pressed against the skin, such as when tangled within clothes, bedding, shoes, towels, or inside work gloves.
Chilean Recluse Spider (Loxosceles laeta)
The Chilean recluse is the last of the three spiders in North America with medically significant venom, the others being the black widow and brown recluse. This species is native to South America, common in Chile, and found in south and eastern Brazil, Perú, Argentina, Uruguay, and Argentina. Unfortunately, it has been introduced into several areas in the United States—including Alabama.
Chilean recluses can be identified by their large size, generally ranging from 0.32-1.57 inches in size (including legs) —one of the largest species of recluse spiders known to exist. Like most recluses, they have a brown color and markings on the dorsal side of the thorax with a violin-shaped pattern.
The Chilean recluse is considered the most deadly of recluse spiders, and its bite can result in serious systemic reactions, and worse, death may occur. However, they are non-aggressive and do not attack or bite unless disturbed. Symptoms of the Chilean recluse’s bite may range from a minor bite with mild skin irritation to severe skin necrosis, called cutaneous loxoscelism. Though the bite may initially be painless, it might eventually grow up to a size of about 10 inches (in severe cases). A few fatalities have been recorded in 3% to 4% of cases studied over 30 years in Chile. If you suspect a Chilean recluse has bitten you, seek medical attention immediately.
Mediterranean Recluse Spider (Loxosceles rufescens)
Almost indistinguishable in appearance from the brown recluse spider, this spider belongs to the Loxosceles genus, which comprises many of the most dangerous spiders in the world. As its name implies, the Mediterranean recluse spider originated in the Mediterranean area but has been introduced into many other areas due to increased human travel and goods transport. In Alabama, they can be found in semi-arid environments and damp areas, including basements, tunnels, and caves.
Both male and female Mediterranean recluse spiders grow to approximately 0.23 – 0.39 inches in length. Like other recluse spiders, they have a brown body and violin mark on their cephalothorax.
Their bite is potentially dangerous, causing typical skin “loxoscelism” effects seen in spiders in the Loxosceles genus. Victims may feel sharp pain followed by a burning sensation from 2 to 8 hours after being bitten. Areas adjacent to the bite often become red and painful. A blister may form, often changing to dark blue with a depressed center. Fatalities rarely occur. However, it is important to seek medical treatment when bitten.
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