Over several months, researchers found and killed over 2,000 Loxosceles reclusa in the “highly infested” home.
A case report details a chilling but fascinating story: a Kansas family unknowingly lived alongside 2,055 brown recluse spiders (Loxosceles reclusa) in their home over five and a half years. Over several months, researchers meticulously tracked and killed more than 2,000 spiders in what was described as a “highly infested” residence.
Spiders often carry a bad reputation, despite their incredible usefulness in controlling other pests. Most species are harmless, but there are a few venomous ones you’d definitely prefer not to encounter inside your house—like the brown recluse.
According to the Illinois Department of Public Health, “Brown recluse are hunting spiders that wander at night in search of prey. Females make retreats in which they hide and ambush prey. A retreat consists of a mat of silk spun in a hidden location such as in a wall void or behind a picture frame.”
Once brown recluses settle in, they’re tough to remove. They hide deep in furniture, cracks, and walls. “They are long-lived, can survive for many months without feeding, and females need mate only once to produce offspring throughout their lives,” the department continues. “So it takes only one, mated female to start an infestation. Once established, they are difficult to control.”
This fact was horrifyingly confirmed by one Kansas family, which included a 13-year-old and an 8-year-old child. They moved into a 19th-century house in 1996, unaware of the eight-legged army hidden within. By summer 2001, they finally realized the spiders they had occasionally seen were Loxosceles reclusa, commonly known as the brown recluse.
One of the study’s authors began collecting specimens, confirming their identity. From mid-June to mid-September 2001, two researchers collected spiders nightly. While many spiders were collected alive, others had to be killed to prevent escape. All were documented.
“In six months, 2,055 brown recluse spiders were collected or killed,” the researchers noted. “842 from sticky traps and 1,213 from manual sampling.” Of the 1,179 manually collected spiders, there were 323 large (27.4%), 255 medium (21.6%), and 601 small (51.0%).
That’s a staggering number of spiders, and a wide range in size. As the collection continued, the researchers observed a decrease in larger specimens.
“The decrease in large and medium spiders from early to late season was probably a result of the natural demographic development through the season and the removal of larger specimens that were easier to detect and capture,” they explained. “Brown recluse spiders can live several years, so the latter reason may be more critical in explaining the proportional dwindling.”
Importantly, the spiders are considered capable of envenomation at about 5 mm body length, which matched the “medium” category. The researchers estimated that about 488 spiders in the home could have delivered venomous bites.
Despite this, the family remained entirely unharmed.
“Despite a conservative estimate of 400 envenomation-capable brown recluses in the Kansas home (≈20 percent of the total captured), no envenomations of the occupants occurred,” the report confirmed.
A similar case in Chile also found hundreds of brown recluses in a home—with no reported bites. This supports the researchers’ claim that spider bites, particularly in regions where these spiders are rare, are often misdiagnosed by medical professionals.
“Considering the number of brown recluse spiders found in the homes in this study without envenomation, for bite diagnoses in nonendemic recluse territory to be correct, nonendemic areas would need to support hundreds to thousands of brown recluse spiders,” the researchers wrote. “In contrast, in nonendemic areas, typically no brown recluse populations are known and verified finds are <10 per state.”
They concluded that medical diagnoses should require verified proof of the spider’s presence before attributing a lesion to a bite.
The Illinois Department of Public Health agrees that the spider’s reputation is often exaggerated: “When they do occur, bites are rarely as serious as they have been portrayed. Some bites produce only localized redness and swelling. Severe necrosis probably occurs in less than 10 percent of cases, and may result more from bacterial infection of the wound rather than reaction to the spider’s venom.”
So while living with over 2,000 brown recluse spiders sounds like a horror movie scenario, this Kansas family’s story paints a different picture—one where even the most feared houseguests may be less dangerous than we think.
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