Spiders, Mites, Ticks, Scorpions, and Others:
Arthropods of the Class Arachnida generally bear eight legs, and the head and thorax are usually fused into a single body section, the cephalothorax. The arachnids generally prey on other arthropods (e.g., spiders), but some are herbivorous (e.g., Spider Mites) and others are parasitic (e.g., ticks). Still other types feed on decaying matter.
Scorpion (Order Scorpiones)
Scorpions (Fig. 7.1) are common at lower elevations and are generally nocturnal. These predaceous arthropods have a stinger at the tip of the tail-like abdomen and should be handled with care. Smaller forms are common around houses and woodpiles.
Spiders (Order Araneae)
The spiders are a diverse group of predatory arthropods. In many habitats they are extremely abundant and consume vast numbers of tiny insects and other small prey. They are also a favorite food of many birds and other insectivorous vertebrates.
Tarantulas (Family Theraphosidae). (Fig. 7.1) Large spiders with very hairy bodies. Although the Tarantula can bite, North American species are relatively harmless. Tarantulas are nocturnal and serve as prey for several large spider-killing wasps, including those of the genus Pepsis . During the day they hide in silk-lined burrows in the ground.
Black Widow Spider,Latrodectus hesperus(Family Theridiidae). (Fig. 7.1) Produces tangled webs made of exceptionally strong, thick silk, commonly occur in buildings and sheds. The female is black with an hourglass-shaped red patch on the underside. The venom is very toxic, and bites should be treated medically. Black Widows are known to catch their prey by "spitting" strands of silk, entangling it.
Orb-weaving Spiders (Family Araneidae). (Fig. 7.1) A large family of spiders that weave the familiar circular "orb" web, which is used to catch flying insect prey.
Wolf Spiders,Lycosaspp. (Family Lycosidae). (Fig 7.1) Terrestrial hunters, often abroad by day. The females of these hairy brown spiders are commonly seen carrying a large, spherical egg case or newly hatched young on their back. Small Wolf Spiders
may be extremely abundant in grasslands and meadows up to 14,000 ft (4,300 m) elevation.
Jumping Spiders (Family Salticidae). (Fig. 7.1) An easily recognized family of spiders with very short legs, which they use to rapidly run and jump in search of their prey. Diurnal, they have large eyes and hunt their prey visually, jumping on it and delivering a paralyzing bite. Some species are brightly colored with red, metallic green, or blue.
Harvestmen (Order Opiliones)
Harvestmen have the entire body fused into a circular or oval shape and commonly have very long legs. Most species are predaceous.
Daddy Longlegs (Suborder Palpatores). (Fig. 7.1) Some Daddy Longlegs huddle together in masses of hundreds in cool, damp spots, their legs resembling masses of brown hair.
Mites and Ticks (Order Acarina)
Mites and ticks are usually small, with very short legs as compared with spiders. They have sucking mouthparts.
Ticks (Families Ixodidae and Argasidae). (Fig. 7.1) Ticks are blood-sucking parasites of vertebrates, to which they attach themselves and feed until they are engorged. In large numbers they may cause temporary paralysis until removed. Tick bites can become infected, particularly when a feeding tick is removed carelessly, its head broken off and left in the wound. Ticks also serve as vectors for disease.
Red-spider Mites (Family Tetranychidae). (Fig. 7.1) An important group of extremely tiny arthropods (less than 0.04 in or 1.0 mm) that are herbivorous, causing severe economic damage to certain crops and cultivated plants, particularly indoors. They are slow-moving and sedentary. Other mites, larger and more active, are predaceous and commonly seen at all elevations on the ground and in foliage. They are usually red or orange.
False Scorpions, or Pseudoscorpions (Order Pseudoscorpiones)
False Scorpions (Fig. 7.1) are small arthropods that lack the tail-like stinger of true scorpions but possess a pair of pincers and otherwise look very much like true scorpions. These animals overwinter under stones and logs, in a silken case.
Wind Scorpions (Order Solifugidae)
Wind Scorpions are a group of large, conspicuous athropods. They are fast-running predators chiefly active at night.
Sun Spiders. (Fig. 7.1) Yellow-brown arachnids that look like large spiders except that the abdomen is segmented, like that of a scorpion, and the head bears large, foreward-facing jaws. They do not produce venom.