Many different arachnids inhabit Pennsylvania’s diverse environments, leading to frequent questions about size and identification. This article identifies the biggest spider species found in the state, focusing on its physical dimensions, preferred habitat, and the risk it poses to humans.
The Largest Spider Species
The biggest spider species in Pennsylvania is the Dark Fishing Spider (Dolomedes tenebrosus). Mature females achieve the most impressive size, with a body length ranging from 15 to 26 millimeters (roughly one inch). Their leg span often reaches 50 to 90 millimeters, or up to 3.5 inches across.
The Dark Fishing Spider is brownish-gray with dark, banded markings on its legs and chevrons on its abdomen. Males are significantly smaller than the females, typically measuring only 7 to 13 millimeters in body length.
Where the Largest Spider Lives
Despite its name, the Dark Fishing Spider is often found far from water, preferring wooded settings and terrestrial environments. This adaptable species commonly dwells on trees, under loose bark, or beneath stones. They hibernate as immature adults through the winter, maturing in the spring, and are often seen from early May through September.
The species is known to be a common household invader, especially in homes located near wooded areas. They frequently enter human-made structures like sheds and basements, seeking shelter in protected areas. Dolomedes tenebrosus is an active hunter and does not use a web to capture prey. Instead, it relies on speed and keen senses to ambush insects, small fish, or tadpoles, moving across the ground or even the water surface.
Other Common Large Spiders
Other large spiders, notably Wolf Spiders from the genera Hogna and Tigrosa, are frequently mistaken for the biggest species. The Carolina Wolf Spider (Hogna carolinensis) is among the largest, with females reaching a body length of 22 to 35 millimeters. This makes H. carolinensis the largest-bodied spider in the state, though the Dark Fishing Spider often has a longer leg span.
Tigrosa aspersa is another common large wolf spider, with females measuring 18 to 25 millimeters in body length. Wolf spiders are ground-dwelling hunters that do not build webs for catching food and are typically dark brown with gray hairs. Female wolf spiders carry their egg sac attached to their spinnerets and later transport their spiderlings on their back.
Assessing the Threat Level
Despite their intimidating size, the Dark Fishing Spider and the larger Wolf Spider species are not considered medically significant to humans. All spiders possess venom, but the potency of these species is generally low, and they are not aggressive. They are shy creatures that will typically flee when disturbed or approached.
Bites are rare and occur almost exclusively when a spider is trapped or actively provoked, such as being accidentally squeezed against the skin. For most individuals, a bite causes localized pain, redness, and swelling, symptoms that are generally comparable to a bee or wasp sting. Discomfort typically subsides within 24 hours, and serious medical consequences are not associated with these common large Pennsylvania species.