Many people are concerned about potentially dangerous spiders, especially the brown recluse, which is often misidentified. This leads to frequent questions about their distribution and identification.
Brown Recluses and Colorado
Brown recluse spiders (Loxosceles reclusa) are not native to or established in Colorado. Their natural habitat is primarily the south-central United States, extending from Nebraska south to Texas and east through Georgia and Tennessee. The environmental conditions in Colorado, including its climate and typical habitats, are generally unsuitable for the establishment of breeding populations of brown recluse spiders.
While it is theoretically possible for a single spider to be transported to Colorado, perhaps through moving boxes or freight, such an isolated incident would not indicate an established presence. The brown recluse spider thrives in warmer, more humid environments with ample dark, undisturbed places to hide, like those found in states such as Missouri or Arkansas. Colorado’s drier climate and different ecological characteristics do not support the widespread proliferation of this species, so reports of brown recluse sightings in Colorado are almost always misidentifications of other common local spiders.
Commonly Confused Spiders in Colorado
Many spiders commonly found in Colorado are often mistaken for the brown recluse due to similar coloration or general appearance.
One such group includes funnel weaver spiders, which are abundant in Colorado and can build sheet-like webs with a funnel retreat. These spiders, including species like the hobo spider (Eratigena agrestis), are typically brown and can be found in homes, leading to misidentification. Their bites are generally mild, often resulting in only localized pain and redness.
Wolf spiders (Lycosidae family) are another common group in Colorado that are frequently confused with brown recluses. These robust, hairy spiders are typically brown or gray and are active hunters, often seen scurrying across floors or outdoors. Unlike brown recluses, wolf spiders have eight eyes arranged in three rows, with two large eyes in the middle row. Their bites are usually not medically significant, causing minor irritation similar to a bee sting.
Yellow sac spiders (Cheiracanthium inclusum) are also present in Colorado and can be mistaken for recluses due to their pale yellowish-tan color. These spiders are known for building small, silken sacs in corners of rooms or under objects. While their bites can cause a localized red lesion and some discomfort, they are not considered dangerous. Recognizing these common Colorado spiders helps clarify why many suspected brown recluse sightings are inaccurate.
Identifying a Brown Recluse
A brown recluse spider possesses several distinct features that differentiate it from other spiders. The most recognized characteristic is a dark, violin-shaped marking on its cephalothorax, the fused head and thorax region. However, this marking can sometimes be faint, and other features provide more reliable identification. Unlike most spiders, which have eight eyes, the brown recluse has six eyes arranged in three pairs, forming a semicircle.
The body of a brown recluse is typically uniform light to medium brown, without any stripes, bands, or patterns on the legs or abdomen. Its abdomen is usually covered in fine, sparse hairs, giving it a somewhat velvety appearance. The legs are slender and lack spines. Identifying these specific anatomical details is crucial for accurate identification, as many other brown spiders lack this combination of characteristics.
After a Spider Bite
If you suspect you have been bitten by a spider in Colorado, general first aid measures can help manage the symptoms. Begin by thoroughly cleaning the bite area with soap and water to prevent infection. Applying a cold compress or ice pack wrapped in a cloth to the bite site can help reduce swelling and discomfort. Elevating the affected limb, if possible, can also help minimize swelling.
It is advisable to seek medical attention if symptoms worsen or cause significant concern. These symptoms might include increasing pain, spreading redness, pus, or if you develop systemic reactions like fever, chills, or body aches. When possible and safe, try to capture the spider that bit you in a sealed container or take a clear photograph of it. This can assist medical professionals or entomologists in identifying the spider, which is important for proper treatment, as self-diagnosis of spider bites can be inaccurate.