The widespread concern about venomous spiders often brings up the question of the Black Widow’s presence in Colorado. This state is indeed home to these arachnids, and residents should maintain a factual understanding of their characteristics and habits. Knowing how to identify the species and where they commonly reside is the first step toward effective safety.
Yes, Black Widows Are Found in Colorado
Black Widow spiders are native and relatively common across Colorado. The species found here is the Western Black Widow, scientifically known as Latrodectus hesperus. This species is widely distributed throughout the western half of North America, including the Rocky Mountain regions and the western Great Plains.
Although widespread, these spiders are often reclusive and go unnoticed. They inhabit both rural and urban environments, successfully establishing populations wherever suitable shelter and prey are available.
How to Identify the Western Black Widow
Correctly identifying the Western Black Widow focuses primarily on the mature female, as she is the individual of concern and is more visually distinct. The adult female is characterized by a shiny, jet-black body and a distinctly rounded, bulbous abdomen. Her body typically measures between 1/4 and 1/2 inch in length, which is significantly larger than the male.
The most recognizable feature is the bright red or reddish-orange marking on the underside of her abdomen. This mark is often described as an hourglass shape, though its appearance can vary, sometimes presenting as two separated spots or an incomplete marking. In contrast, the male is much smaller, often light brown or gray, and lacks the solid black body or prominent hourglass marking.
These spiders construct an irregular, messy web composed of very tough, strong silk fibers. Unlike the symmetrical webs of garden spiders, the Black Widow’s web is haphazardly built and typically located near the ground or close to a sheltered retreat.
Where Black Widows Live in Colorado
The Western Black Widow thrives in dry, dark, and undisturbed environments, which are plentiful across Colorado’s lower elevations and eastern plains. They prefer to nest near the ground in areas that offer protection from predators and the elements. Outdoors, common hiding places include rock piles, woodpiles, under decks, and construction debris.
They frequently seek refuge in human-made structures that provide secluded shelter. This includes storage sheds, garages, outdoor utility boxes, and seldom-used areas like crawl spaces and basements. The spiders tend to build their webs in holes, cracks, and crevices, such as spaces between bricks or pipe penetrations in walls.
Because they are shy and nocturnal, they establish retreats where they hide during the day and emerge at night to hunt. Their prevalence is highest in areas that align with their preference for warmer, drier climates and readily available shelter. These conditions make them common in urban and suburban settings where clutter and outbuildings offer ideal habitat.
Safety Measures and Prevention
Black Widow spiders are not aggressive and typically only bite defensively when they feel threatened or when their web is disturbed. The venom contains a neurotoxin that affects the nervous system, leading to a condition called latrodectism. Symptoms can include immediate pain at the bite site, followed by severe muscle cramps, abdominal pain, nausea, and sweating, which necessitate seeking immediate medical attention.
Prevention focuses on reducing potential encounters by making their habitat less appealing. When working in areas where spiders may hide, such as moving wood or accessing crawl spaces, wear long sleeves and heavy-duty gloves. Reducing clutter and debris around the exterior of the home eliminates many suitable nesting sites.
Indoors, regularly vacuuming or sweeping storage areas, window wells, and garage corners can remove spiders and their webs. Sealing cracks, gaps, and entry points around the foundation and utility lines helps prevent them from moving inside the structure. Shaking out shoes and clothing stored in garages or basements is another simple precaution to avoid accidental bites.