Many people in Michigan are concerned about dangerous spiders. While spiders are a natural part of the state’s ecosystem, understanding which species are truly a concern can help alleviate undue fear. This article provides clear information on Michigan’s spider population and how to respond to a bite.
The Truth About Michigan’s Spiders
Michigan has many spider species, but very few are medically significant to humans. Most spiders encountered in the state are harmless, and their bites typically cause only minor irritation. Severe reactions to spider bites are rare. Spiders generally avoid human contact and bite only if threatened or accidentally pressed against the skin.
Identifying Michigan’s Medically Significant Spiders
The Northern Black Widow (Latrodectus variolus) is the primary medically significant spider in Michigan. Females of this species have a glossy black body, typically with a red hourglass marking on the underside of their abdomen. This marking can sometimes be incomplete or split, and some may have red spots or white stripes. Females are about half an inch long, excluding leg span, while males are smaller and lack the hourglass.
Northern Black Widows build their webs in undisturbed, low-lying areas. Outdoors, these include woodpiles, hollow logs, old stumps, and abandoned animal burrows. Indoors, they may be found in sheds, crawl spaces, and window wells. Their venom is a neurotoxin that can cause severe muscle cramps, pain, nausea, and sweating, though bites are rarely fatal for healthy adults.
Debunking the Brown Recluse Myth
The Brown Recluse spider (Loxosceles reclusa) is often linked to venomous bites, but it is not native or common in Michigan. Any reported instances are usually from spiders inadvertently transported from their native range in the central and southern United States. Therefore, most suspected “brown recluse bites” in Michigan are misdiagnosed, often being other insect bites or skin conditions.
A true brown recluse has a distinct dark, violin-shaped marking on its back, with the “violin” neck pointing towards its abdomen. They also have six eyes arranged in three pairs, unlike the eight eyes found in most spiders. Brown recluses are shy and prefer undisturbed, dark areas like closets, basements, or garages.
What to Do After a Spider Bite
If you suspect a spider bite, especially from a potentially medically significant species, take appropriate action. First, clean the bite area thoroughly with mild soap and water. Apply a cool compress or ice pack for 15 minutes each hour to reduce pain and swelling. Elevating the affected limb, if possible, can also be beneficial. Over-the-counter pain relievers can manage discomfort.
Seek medical attention immediately if you suspect a Northern Black Widow bite or experience severe pain, spreading redness, a growing wound, or systemic symptoms like fever, chills, body aches, abdominal cramping, or difficulty breathing. Also seek medical care if you are unsure about the spider that bit you or if symptoms worsen.