Determining which state has the largest spiders in the US requires understanding how spider size is measured. The impressive appearance of a large spider often results from long, hairy legs stretching its overall profile. The absolute “biggest” spider can be determined in two different ways, which sometimes point to different species.
Defining Spider Size
Spider dimensions are primarily assessed using two metrics: diagonal leg span and body length or mass. Diagonal leg span is the measurement taken from the tip of the first leg on one side to the tip of the fourth leg on the opposite side. This metric tends to produce the most dramatic and largest numbers, making it the one most frequently cited in discussions of size.
Body length measures the main body structure from the front of the cephalothorax to the end of the abdomen. This measurement is more consistent because leg position varies, and the abdomen’s size can fluctuate based on feeding or whether females are gravid. Species with great bulk, like the tarantulas, often top the list when size is measured by mass.
The Largest US Spider and Its Home State
The state that consistently produces the largest spiders by both leg span and sheer mass is Texas, closely followed by Arizona and New Mexico. The species responsible for this reputation belongs to the genus Aphonopelma, commonly known as American tarantulas. These heavy-bodied spiders represent the largest arachnids north of Mexico.
Females of the Aphonopelma genus, such as the Texas brown tarantula (Aphonopelma hentzi), are among the most substantial, reaching a leg span of up to 5.5 inches. These species thrive in the arid and semi-arid environments of the American Southwest, spending most of their lives in silk-lined subterranean burrows. Southern populations, particularly those in Texas, are typically the largest examples found within the United States.
These tarantulas are the absolute heavyweights of US spiders, widely distributed across the Southwest. They are mygalomorphs, characterized by their downward-striking fangs and robust build, which contributes to their considerable mass. This combination of bulk and impressive leg span secures Texas’s position as the home state for the country’s biggest spiders.
Other States with Notable Large Species
Other states host impressive, large-legged species that compete for size when measured by leg span. The Carolina Wolf Spider (Hogna carolinensis) is the largest species of wolf spider in North America, with a leg span reaching up to 4 inches. Although it is the state spider of South Carolina, its distribution spans much of the continental US and southern Canada.
The Golden Silk Orb-Weaver (Trichonephila clavipes) is another large contender, found across the southern US, particularly in warm, humid states like Florida and the Southeast. Females of this species can have a leg span of up to 6 inches, often exceeding the leg span of many tarantulas. While the massive size of its legs makes it appear very large, its mass is much less than a tarantula’s.
The Huntsman spider (Heteropoda venatoria) is an imposing species established in warm climates like Texas, California, and Florida. Known for their long, crab-like legs and speed, they can reach a leg span of 3 to 5 inches. These examples demonstrate that large, visually striking spiders are not confined to one region, but the true giants by mass remain in the Southwestern desert states.
Myth Versus Reality
The sheer size of these large US spiders often leads to misplaced fear about the danger they pose. Despite their intimidating appearance, tarantulas of the Aphonopelma genus are generally docile and non-aggressive. Their venom is considered mild, and a bite is often compared in effect to a common bee sting.
Wolf spiders are not considered medically significant and rarely bite unless physically threatened or trapped. The primary threat from these large species is not their venom, but the large size of their fangs, which can cause a painful puncture wound. Most large spiders prefer to flee or use defensive displays rather than biting humans.