Sun spiders range from about 0.4 to 2 in. in length and are generally uniform in color. They are usually yellow, brown or black, though a few species have patterns. The solpugids are hairy and have spider-like features. They have two closely placed median eyes and eight legs. Their body is divided into the prosoma (thorax) and the opisthosoma (abdomen). Despite the name, solpugids are more like scorpions than spiders in that they have no narrow pedicel.
Their most noticeable feature is their large chelicerae. These structures project in front of the head and each pair is composed of two pieces forming a pincer. Despite their fearsome appearance, they are not poisonous, lacking venom and silk glands. Sun spiders appear to have 10 legs, but the first pair of “legs” are actually pedipalps. These pedipalps are sticky at the ends and are used to position and direct food items to the chelicerae for processing and consumption.
Solpugids are nocturnal hunters and are very swift and agile. Sun spiders have a high metabolism and are very active — thus earning the nickname “wind scorpions.” They live predominantly in desert habitats, and will feed on all types of small arthropods. Larger species will even hunt small vertebrates.
There are more than 50 species in the deserts of the southwestern U.S. They will usually remove the appendages of their prey and consume the head first. Only the liquid and fine particles are actually ingested; the pulp that results after a meal is discarded. There are also species of sun spiders that are more specialized. For example, a species in California will enter beehives and feed on bees, while a Colorado species is specialized in hunting bedbugs.
Mating takes place after the rainy season. Males of this species are smaller than females and have longer legs. Females will eat the male after mating unless the male is quick enough to escape. A mating ritual performed by the males before the act increases their chances of escape. A male lulls the female into a state of lethargy by stroking her. Once docile, the male picks up the female and carries her around for a while. He then lays her on her side and awakens her sexually by stroking the underside of her abdomen. Sperm transfer occurs directly from the male to the female.
After mating, the female constructs a burrow in the ground and lays approximately 50 to 200 eggs, depending on the species. She will then guard the eggs and young for several weeks until the young molt for the first time. The young emerge in about four weeks and will disperse after their first instar. They become sexually mature after nine molts, and will live for about 12 months, depending on the species.
Sun spiders are capable of biting and breaking skin. These wounds can be treated with soap and water and antiseptic to prevent bacterial infections.
Sun spiders should not be handled directly by hand. If they are found around structures, they should be carefully removed with a dustpan or container and returned to the outdoors. Solpugids in general are a beneficial component of desert ecosystems, keeping the population of ticks, mites and other harmful arthropods in check as natural predators.
The first step in managing sun spiders around dwellings is to remove all debris such as loose boards, rocks, stacked wood or any other materials under which they can hide.
Discourage their movement into dwellings by preventing entry by sealing cracks and using weatherstripping around doors and windows. Because sun spiders are independent and solitary hunters, removal or destruction of a discovered individual should take care of the problem in most cases.
In general, pesticides should not be applied to control sun spiders. In fact, they are actually an endangered species in parts of British Columbia. There are no insecticides available that have sun spiders listed on their labels.
However, if for some reason rapid population reduction is necessary, pesticides labeled for scorpions, spiders or centipedes may be used in most states if the site is on the label.