Poisonous Spiders: What You Need to Know

The mere mention of spiders sends shivers down the spine of many, but a select few species, armed with venom potent enough to pose serious health risks, stand out. Among these, the infamous black widow and the elusive brown recluse have captured public attention; however, it's important to recognize that they are but two species in a much broader ensemble of the most venomous spiders.

Understanding the power behind a poisonous spider bite and recognizing the signs can be the difference between a frightening encounter and a life-threatening situation. Homeowners, in particular, should not take the presence of these eight-legged guests lightly. Whether nestled in a corner or lurking in the shadows of your garden, poisonous spiders demand a proactive approach to ensure the safety and well-being of your household.

How can you tell if a spider is venomous?

Determining whether a spider is venomous can often be achieved by examining specific physical features. Venomous spiders tend to have distinctive markings, colors, and body shapes that can help in their identification. For instance, the presence of distinct patterns and bright colors are common signs of venom. Many poisonous spiders are more likely to flee than attack, but they will bite if threatened or pressed against human skin. Observing a spider's reaction to a perceived threat can provide hints, though it's not a definitive method of identification. In addition, most venomous spiders tend to prefer secluded, undisturbed areas like garages, basements, and attics.

What are some of the most venomous spiders in the world?

Spiders are found all over the world, in fact, there are over 3,000 species of spiders in the United States alone. While all spiders have venom that is considered toxic or poisonous, only a handful possess venom that can be dangerous to humans. Here are some of the most common poisonous spiders you should know about:

Brown recluse spider

The brown recluse spider is known for its distinctive violin-shaped marking on its back. This venomous spider can be found in undisturbed areas such as closets, attics, and garages. They are primarily located in the central and southern United States, as the brown recluse prefers warm, dry, and dark environments. What makes the venom of the brown recluse particularly dangerous is its necrotic nature, which can lead to significant tissue damage and, in rare cases, systemic reactions in humans.

Black widow spider

The black widow is a highly venomous spider recognized by the distinctive red hourglass shape on the underside of its abdomen, a feature associated with the females of the species. These poisonous spiders are predominantly found in the United States, particularly in the southern and western regions, thriving in dark, secluded areas such as woodpiles and cluttered areas of garages and basements. The venom in a black widow bite is a potent neurotoxin designed to immobilize their prey, which can be particularly dangerous to humans – especially if the wound is not kept clean.

Sac spider

The Sac spider is characterized by their relatively small size and pale color, although yellow sac spiders have distinctive yellow or pale green coloration. These poisonous spiders are commonly found inside homes, weaving small silk sacs in which they rest during the day in corners, behind shelves, and under leaves outdoors. Their preference for warm, dry environments often leads them into human habitats, where encounters are more likely. Although not as notorious as the black widow or brown recluse, the venom of the sac spider can cause significant discomfort, as it has cytotoxic properties and, in some cases, may result in a small necrotic lesion.

Brazilian wandering spider

The Brazilian wandering spider, known for its potent venom, is a large, hairy spider. Its coloration ranges from brown to blackish, with lighter or sometimes reddish or orangey spots or stripes on its abdomen and legs. These venomous spiders have a robust body structure and can have a leg span of up to five or six inches. They are primarily found in tropical South America, including Brazil, hence its name. Unlike web-building spiders, their nomadic nature means they are often found on the forest floor, under logs or rocks, and sometimes in homes, hiding in clothes or shoes. Their venom contains a powerful neurotoxin that affects the brain's nervous system and can cause serious medical conditions in humans.

Wolf spider

Typically, wolf spiders are brown, gray, black, or tan, with dark markings—most commonly stripes. One of the most notable features of wolf spiders is their eye arrangement. They have eight eyes arranged in three rows: the bottom row consists of four small eyes, the middle row has two very large eyes, and the top row contains two medium-sized eyes. Their bodies are hairy, which can sometimes make them appear larger than they actually are.

Wolf spiders are ground dwellers and do not spin webs to catch their prey. Instead, they chase down or ambush their prey, using their speed and camouflage to their advantage. These venomous spiders can be found globally, thriving in a diverse array of environments, including forests, grasslands, and even suburban gardens, adapting easily to different habitats. While wolf spiders do possess venom, it is primarily used to immobilize their prey and is not generally considered dangerous to humans.

How to help prevent venomous bites in your home

Spiders are among the most common insects homeowners find, but it can be challenging to know if they pose a threat. At Terminix, our experts have decades of experience dealing with poisonous spider control and can help you keep your family protected from these species. With coverage under our PestFree365+ plan, you can get protection from some of the most venomous spiders, like brown recluses and black widows.