Spider Identification Guide

Black Widow Spider

Appearance:

Black widow spiders are known for the females’ unique appearance and tendency to eat their mates. They are considered the most venomous spiders in North America; however, their bite is rarely fatal to humans. Male and female black widows look different. Female black widows are about 1.5 inches long. The males are about half the size of females and are lighter in color, with red or pink spots on their backs. The females are the most distinctive, with shiny black bodies and a red hourglass-shaped marking on the underside of their round abdomen. An important characteristic of this spider is its comb foot. This comb, a row of strong, curved bristles is located on the hind pair of legs and is used to throw silk over captured prey. Black widow spiders eat other spiders and insects that get caught in their webs. The female spider hangs upside down from her web as she waits for her prey. By doing this she shows off her bright markings, which are a warning to predators that she is toxic.

Life Cycle

Black widows are primarily solitary creatures, with the exception of late spring when mating occurs. Female spiders can live up to three years. Males will live for one or two months. The female often kills and eats the male after mating, providing her with a ready supply of protein which is necessary for the offspring developing inside her. The female creates light tan papery, round and smooth egg sacs that contain between 200 and 900 eggs each. The eggs hatch after about 30 days. The baby spiders are cannibalistic and few survive the three-month period of development to adulthood.

Brown Widow Spider

Appearance:

The brown widow is slightly smaller and lighter in color than its black cousin; the color can range from tan to dark brown to black, with shades of grey. Like its black cousin, it has a prominent hourglass-shaped design on the underside of the abdomen; the brown widow’s hourglass, however, is usually a vivid orange or a yellowish color. It also has a black-and-white geometric pattern on the top side of its abdomen. As the spider matures its coloring darkens and this pattern becomes less noticeable. Also, they have distinctive stripes on their legs. Brown widows are most often identified by their egg sacs. Their distinctive round and spiked eggs sacs, differentiates them from the black widow egg sacs that are round and smooth in appearance.

Life Cycle

Brown widows live from 1 to 2 years and they produce approximately 20 egg sacs containing 120-150 eggs per sac over a lifetime. Spiderlings will hatch in approximately 14 to 21 days but remain inside the egg sac for 4 days to one month. They will then emerge from the egg sac, molt and begin eating but remain in the nest area for several weeks after which they will perform their amazing, ballooning act, as they instinctively venture into the world on favorable winds, looking for food, water and safe harborage. This species can breed all year long.

Red-Back Jumping Spider

Appearance:

There are many different kinds of jumping spiders but in California, the red-back jumping spider is the most recognizable. Jumping spiders average about 3/8″ in length and the female spider is generally larger than the male. They are typically brightly colored, sport very unique patterns, are hairy and sometimes thick bodied. Four pair of eyes give it extremely sharp 360-degree vision. It can see better than almost any other animal of the same size. Having the ability to turn its breast around 45 degrees is another of it’s amazing talents. The back of a red-back jumping spider is distinctly red, with a black strip if it is a female. The rest of the body is usually entirely black. This tiny spider is a daytime hunter and will jump long distances (5 times the length of its own body) to catch its prey. Prey being small insects. It does not spin webs but creates a funnel shaped silken nest in which to hide and where the females lay their eggs.

Life Cycle

Before mating, the male walks toward the female, then backs away. He performs a kind of zigzag dance, and some males produce a sound by twitching their abdomens while dancing. Sometimes the male is killed after mating. A female jumping spider builds a silk case around her eggs. She will then stand guard over them until they hatch. Young jumping spiders emerge from the egg sac looking like miniature versions of their parents.

Orb Weaver Spider

Appearance:

The orb weavers (Araneidae) are one of the three largest spider groups. Their webs consist of radiating strands, like spokes of a wheel, and concentric circles. Most orb weavers build their webs vertically, attaching them to branches, stems, or manmade structures. Webs may be quite large, spanning several feet in width and round in shape which is where this family of spiders gets its name. Orb weaver spiders possess eight eyes, arranged in two rows of four eyes each. Despite this, they have relatively poor eyesight and rely on vibrations within their web to alert them to food. Orb weavers have four to six spinnerets, from which they produce strands of silk. Many orb weavers are brightly colored, and have hairy or spiny legs.

Life Cycle

Males are much smaller than females, and after mating may become her next meal. The female waits on or near her web, letting the males come to her. She lays eggs in clutches of several hundred that are cocooned in silken sacs. In areas with cold winters, the female orb weaver will lay a large clutch in the fall and wrap it in thick silk. She will die with the first frost, leaving her babies to hatch in the spring. Orb weavers live, on average, one to two years.

Wolf Spider

Appearance:

Wolf spiders are usually, brown, grey, black or tan, with dark markings (usually stripes). Their coloring is an effective camouflage, helping them catch their prey and keep safe from predators. They range from a quarter of an inch to over an inch long, with males usually smaller than females. They have a distinctive eye arrangement, where the front row is composed of four small eyes of roughly the same size arranged in almost a straight line. The back row is arranged in a V-pattern with the point next to the back row. Wolf spiders have excellent night vision, and primarily hunt in the dark. They are easily detected at night due to their eye shine.

Life Cycle

The males signal their interest to females by waving their pedipalps (short, sensory appendages near their mouths) in special patterns or banging them together. After mating, female wolf spiders lay several dozen or more eggs and wrap them in silk, creating an egg sac. Female wolf spiders carry their egg sacs attached to her spinnerets (silk making organs). If the female loses her egg sac, she will search for it. Females are known to be most aggressive when carrying their egg sacs. After hatching, spiderlings climb on their mother’s back and she carries them around for several days. The baby spiders, then migrate to new territories by the process of ballooning. (Spinning silk threads that catch a friendly breeze, carrying them away.) Male wolf spiders typically live for one year or less, while females can live for several years.

Desert Recluse Spider

Appearance:

The Desert Recluse is found in the Sonoran and Mojave deserts, in the foothills of the lower Joaquin Valley and areas close to the Mexican border. They prefer to live in remote unpopulated areas. These spiders are nocturnal, meaning they only come out at night and they live under rocks and in old animal burrows. The average size of a mature Desert Recluse spider is approximately 1/2 of an inch, with a leg span of 1.5 to 2 inches. Male and female are similar in size. Desert Recluse spiders, and other related recluse spiders, have six eyes arranged in three pairs of two. This is a unique feature, since most spiders have eight eyes. Its’ legs are quite long and almost hairless, and with legs spread outward the spider may have a diameter of less than 1.5 inches. The cephalothorax is round in appearance and the abdomen is narrow and covered with very short hairs. This spider can be yellowish tan to dark brown in color. It is different from other recluse spiders in that it does not have the typical violin marking on its’ abdomen. The dark violin marking will appear on the top of its’ cephalothorax.

Life Cycle

A female Desert Recluse deposits 40 to 50 eggs inside a single silken egg sac. In her life time she will produce 1-5 of these egg sacs. The spiderlings go through their first molt inside the egg sac then hatch out in about two weeks. After emerging, they go through 6 or 7 more molts in the next 7-12 months before becoming adults. Adults live about 1-2 years.

Warning: These spiders may bite! Desert Recluse spiders are normally timid and prey on other insects. Man is not on their menu. If disturbed, they will defend themselves and their bite is venomous. Symptoms of a bite can range from nothing, to a wound that can become life threatening.

This spider is often mis-identified as a deadly “Brown Recluse”. (see below)

Common House Spider

Appearance:

The Common or American House Spider is a nuisance pest and poses no threat to humans. If trapped it may bite. It is aptly named as it is most often found indoors. The adult female of the species is approximately 5-8 mm (3/16 – 5/16 in) in length with a spherical (round) abdomen. Males have elongated abdomens and range from 3.8mm to 4.7mm (1/8 to 3/16th in) in length. These spiders have eight eyes (the 2 lateral pairs almost touch) and their 4th pair of legs has a row of serrated bristles. Both male and female are yellowish brown in color with their abdomens being off white with a few dark stripes meeting at an angle.

House spiders randomly select sites for their tangled webs. Insides homes, these spiders find it hard to survive because of low humidity and few insects they consider food. Outside they can be found around windows and in eaves, especially where a light source attracts their prey.

Life Cycle

Female common house spiders are usually the initiators of mating activity and are not aggressive towards the male. It is not unusual for male and female house spiders to live together on the same web. Mating may occur at any time of year. Common house spiders deposit as many as 250 eggs into a silken sac. These sacs are brownish in color and shaped like a flask. Females produce up to 17 of these sacs during their lifetime, resulting in more than 4,000 eggs. Within a week, spiderlings hatch. Adult spiders may survive up to a year or more.

Creatures misnamed as Daddy longlegs include:

The Crane Fly

Cellar Spiders

California Ebony (Black) and San Diego Bronze Tarantulas

Appearance:

Solitary hunters, these tarantulas, both about 2 inches in length, live in holes in the ground, or occasionally amid rocks, on dry, well-drained grass-covered hillsides or oak-filled woodlands and even desert environs. Tarantulas have poor vision, so they depend on the silk they deposit on the ground around their burrows to send a vibration, signaling that prey is within their reach. Their basic diet consists of beetles, grasshoppers, lizards, mice, scorpions, spiders and other insects. Tarantulas have eight legs, two pedipalps (claws), 8 eyes and are covered with hairs (used to assess their environment since their eyesight is poor and it serves as a defensive mechanism). These spiders have two large, prominent fangs for injecting venom into prey. The venom not only helps to immobilize prey, but also liquefies and digests the soft insides. The Ebony Tarantula is varied shades of black and grey whereas the Bronze is dusky brown to almost black.

Life Cycle

In the fall, after heavy rains, mature males emerge from their burrows seeking females. Male tarantulas take 7 to 10 years to reach maturity (mating age). Males create a ball of webbing upon which they deposit a small amount of sperm. They carry this ball in their pedipalps as they go looking for a female. When they find a female’s burrow, they tap on the silk lines outside of the female’s burrow to get her attention. If the female shows interest, the sperm will be deposited, and the male will try to escape quickly. Most males, even if they are not eaten by the females, die within 2 or 3 months. Female tarantulas produce an egg sac containing anywhere from two to more than 100 eggs. They lay their eggs within their burrow, in an area lined with their silk. Then cover them with more spider silk to form an egg sac. She will guard her eggs until they hatch. Female tarantulas have been known to live up to 25 years.

Brown Recluse Spider

Appearance:

These typically brown to grayish colored spiders have a body length of about 3/8″ inch (but can grow larger), with very long legs. They have six eyes arranged in pairs (dyads) with one middle pair and two side pairs. These spiders usually have markings on the top side of their cephalothorax, with a black line coming from it that looks like a violin with the neck of the violin pointing to the rear of the spider, resulting in the nicknames of fiddle back spider, brown fiddler, or violin spider.

Life Cycle

The female will lay 40 to 50 eggs in a silken casing, producing 1-5 casings during her lifetime. The spiderlings hatch and go through one molt inside the egg case before emerging into the world. After emerging, the instars go through 6-7 more molts in the nest during the next 7 to 12 months before becoming adults. The adults live 1-2 years.