This is a partial list of those spiders which are frequently seen in the urban Los Angeles area and surrounding hills. A more complete list has been compiled for all of California by Steve Johnson and Don Boe. This list is available from the author.

Illustrations for this work will be scanned into this text as soon as practical. For illustrations to this work the reader should consult:

Insects of the Los Angeles Basin, LA Co. M.N.H.

Spiders And Their Kin, by H. Levi, Golden Press, N.Y.

How To Know The Spiders by B.J. Kaston, Pictured Key Nature Series, Wm. C. Brown, Dubuque, Iowa.

For a more technical reference see: Spider Genera of North America by V. Roth, available through the American Arachnological Society, C/o Jon Reiskind, Department of Zoology, University of Florida, Gainesville, FL. 32611.

Family Theraphosidae, the tarantulas

These spiders are common in the deserts and dryer mountains. We occasionally see a few rare specimens in the LA basin. They dig a large burrow that is usually covered with a thin veil of silk when occupied. Tarantulas are nocturnal sit-and-wait predators, remaining in the immediate vicinity of their burrows. The large black males can often be seen wandering about in search of females; the lighter gray/brown females and immatures will also wander following a disturbance. Our tarantulas have venom, which is considered to be relatively non-toxic to humans. Prey is attacked and subdued by force and crushed in the massive fangs. We have three or four reported species; two are common. In Aphonpelma eutylenum (also known as Rhecostica) the males mature in the fall; A. reversum matures in mid summer. Males and females are generally about two inches in length.

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Family Ctenizidae, the trapdoor spiders

Bothriocyrtum californicum, the California trapdoor spider: Trap door spiders are locally common on grassy hillsides throughout our area, but are very seldom seen. The cork shaped, thin doors of these spiders are camouflaged with dirt and leaves woven in, making the opening to the burrows difficult to see. To find them you must search for the outline of the burrow, usually a "D" shaped flat area along a road cut or in short grass, between 1/4 and one inch in diameter. Or a quick search by flashlight at night will sometimes show up the open doors and protruding legs of the waiting spiders. When found, the spider will usually fight to keep the burrow closed. On bare embankments, the silk lined burrow may be washed out to form a short 'chimney'. Occasionally the active black males are seen wandering about in the spring and immatures will relocate following a disturbance. Eggs and young are kept in the bottoms of the one inch diameter burrows and the young disperse during the fall rainy season, building burrows near the female's entrance. The young of spiders in this family are known to disperse by ballooning. Whether this applies to Bothriocyrtum is not yet known. Females can be over one inch long and have a dark brown carapace and legs with a gray or tan abdomen. Adult males are more slender with longer legs and a smaller, dark body. Their first legs have a characteristic crook on one joint.

There are about six trapdoor spiders in our area. Most are 1/4 to 1/2 inch long and build silk lined burrows on moist hillsides. Some species build nests with a "purse type" opening. Road cuts are generally the best places to locate the often-exposed burrows.

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Family Dysderidae

Dysdera crocata: The two-tone red/brown and tan body and forward projecting fangs readily identify these European imports. There appear to be four book lungs on the underside of the abdomen; two are actually tracheal spiracles. The cephalothorax of the young may be bright red. D. crocata feed almost exclusively on sow bugs (Porcellio sp.) and may be found under moist logs, boards and rocks alongside their favorite prey. Sacs are built to molt and lay eggs in. Males are slightly larger than females and are very aggressive in courtship. Adults tend to be about 1/2 inch long.

The Segestriidae are occasionally placed in this family.

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Family Filistatidae

Seldom seen, these large spiders can be common in crevices in trees and around homes in our mountains and dryer areas. Where they occur they may be seen at the entrances to their nests at night. By flashlight the closely grouped eyes glisten white against the velvety black body. We have one reported species, Filistata hibernalis which reach one inch in body length. They build woolly webs made of lines radiating from a round entrance. Males tend to be lighter colored and have extremely long pedipalps. Younger spiders are lighter in color, generally brown or dark gray. Filistatids grow slowly and may live for many years.

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Family Segestriidae

These slender reclusive spiders build webs similar to the Filistatids, often in holes on trees. In some moist areas they may be fairly common, though they are seldom seen and are difficult to extract from their retreats. They are recognized by the web and tubular retreat, their slender bodies and oval shaped abdomens. When resting, the first three pair of legs are directed forward. The fangs project forward as in Dysdera crocata, a close reletive. Two species are reported here; Ariadna fidicina and Segestria pacifica.

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Family Uloboridae, feather legged spiders

The webs of this family lack the sticky silk of the other orb weavers. Members of this family also lack poison glands.

Ulobarus diversus is often seen in gardens where they build horizontal orbs. They tolerate dry conditions well and will frequently build the orbs on house plants. Uloborids occasionally occur in nurseries and garden departments where they apparently feed on root gnats (Sicaridae). These spiders are generally 18 to 1/4 inch long; and are brown or yellow. Males are orange or brown and smaller than the females.

Another group in this family is present in southern California. The ray spider, Hyptiotes gertschi, builds a reduced web consisting of four radii forming a triangle with cross threads. The spider sits at the apex of the triangle holding the web taut. When an insect touches the web, the spider releases the tension further tangling the prey. Some local species build webs consisting of only a single line. Hyptiotes are very small spiders, hardly over 1/16 inch. They are found in moist, protected canyons along the coast.

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Family Oecobiidae

Oecobius sp.: These tiny spiders make an often soot covered, nickel-sized web on walls and tree bark. Frequently numerous, they feed on ants and other small insects and are very commonly seen running about indoors where they feed on ants and possibly fleas. Males and females are both about the same size, under I/8th inch. Two species have been reported here.

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Family Dictynidae

These tiny spiders are occasionally seen on windows where the small, flat irregular web often collects dead insects. They can be recognized by the light gray color, oval abdomen and a web with a net like or ladder-like construction.

Dictyna calcorata is common; males have a huge palpal spur which curves back over the cephalothorax and will occasionally co-inhabit the female's web. Other species are common on twigs and grass seed heads over water where they build ladder-like woolly irregular webs. Locally, we have about fifteen species.

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Family Loxoscelidae, recluse spiders

Native Loxosceles species are common inhabitants of our deserts where they may be found under trash, rocks and in fallen yucca stalks. They are extremely rare in the LA basin area. A south American species, L. laeta, has been established in parts of Alhambra and San Pedro where they may be locally common in commercial buildings. In South America, L. laeta is reported to be dangerously venomous; bites produce large necrotic areas often requiring surgery to heal. The eastern U.S. species, L. reclusa, has a similar reputation and is occasionally brought into this area by immigrants but it has not been reported to be established in our area. All of these spiders prefer dry dark recesses to build their loose, small webs. They are all uniformly tan or brown with a darker violin shaped mark on the carapace, (pale in our desert species). Males resemble females; both are up to 1/2 inch long.

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Family Pholcidae, the long legged cellar spiders

Pholcus phalangioides: This imported spider is often seen in homes where it is the major contributer to ceiling cobwebs. It is most common under the eaves of homes in tree-shaded neighborhoods. Pholcus phalangioides is known by its drab grey-brown and elongate abdomen. Another similar species, Holocnemus pluchei is very common in the central valley of California and only very recently has been noted from this area. Holocnemus, also known as the marbled cellar spider, has banded legs and a distinctly marbled abdomen, the underside of which is black. The web is a fine dome, often with an inverted-cup shaped retreat. It is expected that this spider will eventually displace Pholcus as the local 'cellar spider' when it becomes established. It was hoped that this spider would displace the black widow in many areas when it became established; however this has not proven to be the case.

There are about ten other species of pholcids, most with globular abdomens and difficult to tell apart. These tend to occur under rocks, wood and in rodent burrows. Our commonest one is Physocyclus californicus. The males of all of the Pholcids are similar to the females and sometimes have pedipalps nearly as large as the abdomen.

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Family Theridiidae, comb footed spiders making an irregular or space filling web

Theridion murarium: These tiny European spiders commonly build webs among house plants and along shaded window ledges and stairs. They have the globular abdomen common to most of theridiids. A pattern of stripes on the sides of the abdomen point to a central row of converged spots. Males may be more slender but with legs of equal length to the 1/8th inch females. There are 26 species of Theridion reported from California with about 17 occurring near here.

Achaearanea tepidariorum, the house spider: This is an imported spider with world wide distribution. In southern California this spider is more common in gardens, on trees, walls and buildings. It hangs in the center of its web with its legs characteristically folded over its carapace, often with one or more grey to reddish-brown, papery, teardrop shaped egg sacs. Achaearanea may be distinguished from the similar Tidarron by the gray striped abdomen with a pattern of chevrons near and above the spinnerets. Males have legs similar in length to the 1/4 inch females, but are reddish brown and more slender. We have several other species of Achaearania in southern California.

Steatoda grossa, false black widow: California has fourteen species in this genus. S. grossa is a European import and is extremely common around urban areas. The webs are sometimes similar to those of the black widow, but with much finer threads and usually built in moister microhabitats. Steatoda grossa is reputed to attack black widows. The body can vary from gray with white markings to all black. The usual pattern is a white horseshoe-shaped stripe across the front of the abdomen with a row of white spots down the back. Males are frequently found wandering into homes in the fall. They are quite unlike the females, often having light colored stripes on the thin legs and small abdomen. Large females may be over 1/2 inch, males are quite variable in size, but generally slightly smaller. Other members of this genus are found under tree bark and rocks in our mountains and deserts and are frequent ant predators.

Latrodectus hesperus, black widows: This is the LA basin's only common, dangerous spider. Black widows are surprisingly numerous in the LA basin. A walk along commercially developed streets at night will frequently turn up one in her web every few paces. The webs are large, roughly triangular, and lead to a usually egg-shaped retreat in a hole or crevice. One or more tan, 1/2-inch diameter egg sacks are usually present in the webs of mature females. Black widows are quite common under picnic tables and park benches. They often reach high densities on rocky hillsides and along road cuts. Latrodectus starts life as a tiny gold and white striped spiderling. Later immature stages are red, white and black striped. The small males retain the immature stripes while the mature females become all black except for the red hourglass and occasionally some white and red markings on the top of the abdomen. The slender males are up to 1/4 inch (large specimens) while females may be up to 5/8 inch long. The large size is one reason for this spider's reputation; its fangs are large enough to penetrate all of the layers of human skin. Latrodectus venom is strongly neurotoxic and can cause muscle cramps, convulsions, nausea, vomiting and fever. Bites are usually not fatal to healthy adults. The venom may be a deterrent to predation from mice and birds; red and black are common warning colors.

Tidarren sp.: These spiders closely resembleAchaearanea, but have a white stripe on a brown or yellow abdomen in place of Achaearanea's gray chevrons. The irregular web is built on buildings, rocks and trees and commonly has a central leaf retreat under which the female rests and deposits her round papery egg sacks. The orange or brown males are quite small, hardly larger than the newly hatched young, and difficult to find. Often they have only one palp when mature. Adult females are up to 1/4 inch long. We have at least two species locally.

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Family Oxyopidae, the lynx spiders

Peucetia viridens: This brilliant green spider is often seen in gardens sitting on flowers or foliage. It can be very common among prickly pear stalks. Most specimens may have pink or red markings, especially around trees with red twigs or bark. Immatures wander around hunting in lush foliage or sit and wait near flowers. In the fall the adult females usually build an irregular web around their single large fluffy brown egg sac. The egg sac is vigorously defended until the young hatch and disperse. Adult males are similarly large, up to about 3/4 inch. P. longipalpus is a slightly smaller, similar species.

Oxyopes sp.: We have several other common lynx spiders, 0. scalaris, O. tridens and 0. salticus are often seen hunting in tall lush grass. These small tan or brown spiders feed voraciously on small flies and mosquitoes. Adult males usually have a black or brown "face" with dark pedipalps. They are otherwise similar to the females. Both are about 1/8 to 3/16 inch long. One other species, Hamataliwa grisea is small, very cryptically colored and resembles a twig bud, hence is seldom seen.

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Families Thomisidae and Philodromidae, the crab spiders

Misumenoides formosipes, Misumenia vatia: These are our two common, large, flower spiders. They both tend to be found on flower heads where they are sit-and-wait predators. These spiders have the ability to slowly change color to match the color of the flower they are on; white, pink, and yellow specimens are commonly seen. M. formosipes usually has contrasting patches of darker color on the abdomen and the carapace is more flattened with a white ridge below the eyes. Males of both are much smaller with long slender legs and a darker finely marked body. Females may be up to 1/2 inch in body length. There are many other species similar to these which occur here.

Xysticus californicus: We have several species of dark brown crab spicers in California. There are about nineteen species in this genus; nine are local. X. californicus is the most common. They are often seen under bark where the dark brown mottled colors and flattened, almost tick-like body blend almost perfectly with tree bark. Males are similar to females and about 1/4 inch long.

Tibellus sp.: These slender, straw-colored spiders are often found in tall grass throughout Southern California. They are active and can quickly blend in with the blades of the grass they frequent. Though usually seen in the day they are mainly nocturnal. T. californicus is probably the most common but T. chamberlini is also reported.

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Family Linyphiidae, the bowl and doily spiders

Members of this large group of mostly small spiders are difficult to identify. Linyphiids build sheet webs that are usually surrounded by a tangled mass of irregular threads. The spider waits below the sheet attacking small insects, which strike the irregular web and fall onto the sheet. Locally we have several common species. A small brown and yellow one often seen below its web on branches is Frontinella pyramitela. Another large silver and yellow species is common in our moist canyons. Male linyphiids are similar in size to the females with larger heads, smaller abdomens and darker colors. They often cohabitate in the webs with the females.

There are also many species in the closely related Micryphantidae. These tend to be very tiny and are often seen in leaf litter or among stream rocks. Eriyone dentosa often balloons about making strands of gossamer which stream from leaves and branches. The tiny brown males of another common species are often seen wandering about on walls in search of females.

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Family Clubionidae, the sac spiders

Cheiracanthium sp.: There are two common speciesof yellow sac spiders, differing only in genitalic characters. Both are pale greenish yellow or tan and up to 1/2 inch long. C. mildei is the more common and often wanders into homes where it builds a resting sac, frequently in the corners of rooms or in unusual crevices in household appliances. C. inclusum tends to occur in gardens; both feed at night by wandering about on branches. They are often found in high densities in fly infested areas where they wander to the ends of twigs at night in search of roosting flies. Gardeners occasionally receive bites attributable to this spider. These bites tend to form a small sore, which is slow to heal. Males are similar in size to females and are darker and more slender.

Castianeira sp.: We have at least four species locally. C. occidens is about 1/4 inch long and somewhat resembles the gnaphosids, with a narrow head region and small eyes, a dark body with white markings and a bright red/orange stripe on the rear portion of the abdomen. Several other species are present. Some may have dark bodies with a "tiger striped" abdomen. Others are ant mimics. All are fast runners. Adult males resemble females.

Trachelis pacificus, T. californicus and T. deceptus: These mahogany and tan spiders commonly live under bark and in leaf litter. Trachelis is occasionally seen near our foothills and woods. Males are similar to females or larger, both are 1/4 to 3/6 inch long. Trachelis tends to resemble Dysdera crocata but has downward pointing fangs, eight widely spaced eyes and only two book lungs. Two-tone (red/tan) spiders wandering about on walls at night are generally Trachelis.

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Family Mimetidae pirate spiders

These spiders resemble theridiids and are often found in their webs. They feed exclusively on other spiders and are reported to be effective in feeding on young black widows. The attack is a combination of a slow stalk and movements which imitate prey. When close, mimetids usually bite the prey at the base of one leg. Occasionally mimetids only get away with a single leg which they will feed on before resuming the stalk. Mimetids can be recognized by the elongate head and thorax, globular or somewhat triangular abdomen and legs with long middle segments commonly held folded over the head. The legs have a peculiar pattern of leg spines consisting of a repeating series of spines of decreasing length. Our common species is Mimetus hesperus.

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Family Salticidae, the jumping spiders

Most of these spiders are active during the day and move about on walls and branches in a series of short jumps. The large front eyes are capable of good binocular vision and give them an intelligent appearance, often heightened by tufts of hairs resembling eyebrows.

Phidippus johnsoni. These are large and aggressive jumping spiders reaching almost 3/4 inch. They are readily identified by the female's red and grey coloration, males being large with a black carapace and a red abdomen. Often seen on prickly pear or wandering about on our hillsides; they are occasionally found in gardens. Phidippus commonly builds thick white sacs in low vegetation or under rocks in which they molt, mate and lay eggs. Several smaller species may be similarly colored. There are about 16 species of Phidippus in California.

Thiodina sp. These jumping spiders are seen in foliage in the daytime. They are often common in gardens. The large dark, spotted head and pale body identify them. Males and females are both 1/4 to 3/8 inch. The tiny newly hatched young are almost transparent, allowing the careful observer to view the movements of the dark eyes within the spiderling's head. These, and other salticids, can often be seen in vegetation at night hanging from short lines. This may be an ant avoidance technique.

Menemerus bivittatus: Constantly in motion, these 1/4 inch spiders are found on sunny walls of buildings across the U.S.. Adult males are slightly larger than the females and are sometimes referred to as zebra spiders. Females and immatures are a mottled gray with black stripes along the sides of the carapace. Both sexes are completely diurnal and spend the bright part of the day on sunlit walls hunting flies.

Metaphiddipus vitis: These small iridescent gold and white spiders may be found wandering about on lush vegetation. They are fairly common throughout our area. Other similarly colored jumping spiders also occur here.

Habranattus schlingeri: Occasionally these small black and white jumping spiders reach high densities in lawns. When approached they move deep into the grass, emerging some distance away. They are quick jumpers, making them difficult for birds (and you) to capture. Males resemble females. Both are under 1/4 inch.

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Family Araneidae, orb weaving spiders

Cyclosa sp.: We have three species of these common orb weavers. They are easily recognized by the usually vertical string of old prey items, egg sacs and web remains that the spider hides in, often so well that even up close it is hard to recognize the 3/16 inch spider from the debris. All of the web but the debris string and a single horizontal line is taken down every night, the old web material being added to the debris string. As with many other well-camouflaged spiders, Cyclosa will usually remain motionless in the web, even when prodded. Occasionally loose aggregations of these spiders are found suggesting the beginnings of colonial behavior. Our common species is C. turbinata, but C. conica is often seen, C. walckenaeri is rare in our area.

Neoscona sp.: Our most obvious and common orb weaver. Neoscona builds large web in the early evening and often remains hanging in the web throughout the day. We have at least two species the most common being N. oaxacensis. The color can vary from pale yellow to to almost completely black, the common colors being red-brown with a characteristic abdomen pattern.

Neoscona crucifera is a species that has recently expanded its range and is now the predominate garden spider in many areas.

Araneus sp.: This is a very large genus of spiders, locally we have one very common species; A. gemma, perhaps the heaviest north American orb weaver. It's round, humped abdomen is usually pale colored, tan yellow or greenish, with a single thin median white stripe. It builds a large orb from trees and buildings in moister parts of the valleys and canyons, spending the day hiding in a loose nest made of leaves and silk, usually under an overhanging ledge or branch. Another species, A. andrewsi, is darker, slightly smaller and hairy. There are nine species reported for our area.

Argiope sp. Giant garden spiders

Southern California has all three of the species of giant garden spiders found in the U.S.. A. argentata is the most common, and frequently seen in grassy areas along the coast, especially among prickly pear cactus patches. Its silver abdomen has a row of tubercles along the rear edge. There is frequently an X-shaped silken pattern in the web, usually appearing as an extension of the legs. A. trifasciata and the yellow and black A. aurantia are also found in our moister areas, especially along the coast. Males of all three are much smaller than the one to one and one half inch females and are often seen in or near the mature females' webs.

A closely related spider, Gea heptagon, is often seen in its low web in tall moist grass, especially along the coast. It drops to the ground and changes color to a dark muddy brown when disturbed.

Metepeira sp.: These spiders build a permanent composite web made of a more or less irregular space web with an attached orb. The spider rests in an inverted cup shaped nest in the center of the space web connected to the hub of the orb by a single signal line. Eggs are woven into the nest material. Adult males are much smaller than the 1/4-inch females and rarely seen. A leaf shaped pattern on the back of the abdomen is very characteristic of this genus. We have six species locally, here and in our mountains and deserts.

Zygiella x-notata: This orb weaver is often extremely common around boats and docks throughout the world. The web has a characteristic missing segment and is up to 12 inches in diameter. The spider usually rests in a retreat above the web in the day with a signal line connecting it to the hub. It rebuilds the web at dusk. The abdomen is gray with a characteristic pattern and is smooth and shiny, somewhat like an engorged tick.

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Family Tetragnathidae, long jawed orb weavers

Six species of spiders in this family are reported from this area. They mostly build orb webs over or near water and very closely resemble each other. One species, Tetragnatha laborosa, is common all over the U.S. and is occasionally seen on moist hillsides or watered lawns. Other species are commonly found at night among stream boulders and cattails. The webs are up to 12 inches in diameter and usually positioned horizontally. These spiders feed mainly an mosquitoes and other long legged flies. Males are large, active, and found throughout most of the year. Both sexes are 1/2 to 1 inch with very long legs, usually held close together in a straight line against a twig or blade of grass. Though the large forward projecting fangs are ominous they are incapable of piercing the skin. Seven species occur in California; probably five occurring here.

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Family Agelenidae, grass spiders

These spiders build sheet webs, usually with a tubular retreat, upon which they run out to catch insects that fall onto the web.

Agelenapsis aperta: These spiders build funnel-shaped webs in tall grass which may be up to two feet in diameter. The tube of the web usually runs down into rodent burrows making the spiders difficult to extract. The long legs and spinnerets, dark gray color and large webs in sunny locations identify these 3/4 inch spiders. Palps of the large adult males have a long, curved black tube forming a single coil. Adult males may be seen in the spring and early summer.

Hololena curta: One of our most common and visible spiders. Hololena seems to prefer dark shade and occasional moisture, provided by our ornamental plantings and lawn watering. The sheet webs are built on shrubs, branches and buildings, usually with retreats running into crevices or leaves. An irregular tangle of trip lines extends above the sheet, often over a foot up and attached to overhead structures. Juniper shrubs are a favorite building site; the dense foliage apparently affords protection from feeding birds. Adult males are large and in both sexes the adults are usually a very dark brown. Adults vary in size from 1/4 to 3/4 inch, depending on food and water availability. Males and females mature in the fall and may wander into homes.

Tegeneria sp.: Two species of Tegenaria are common in urban California, the one here is usually T. pagana, though the European T. domestica is also found. These soft, velvety, dark gray spiders are often seen under boards, wood and rocks in gardens in our urban areas. The 1/4 inch males are slightly smaller and more slender than the females.

Calymmaria sp.: The webs of these small spiders are about 4 to 5 inches in diameter and consist of a cone shaped structure point down under an overhang, The spider rests above this on a second platform placed against the overhead surface. Calymmaria is locally quite common on trees and rocks in moist canyons. Twenty four species are reputed to occur in California.

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Family Gnaphosidae, ground spiders

Dark colored, oval spiders with a narrow head and cylindrical spinnerets. Gnaphosids often wander into homes at night. We have many species of this family; the two most commonly seen species are the 1/4 inch pink-marked Herpyllus propinqus and a small Serqiolus sp. (also called Poecilachroa). All are found under boards and rocks and run well. One genus, Cesonia, is strikingly marked with black and white stripes.

Scotophaeus blackwalli is another very common species of household spider. This medium sized brown European import often is found in bathtubs and sinks.

Lycosids, the wolf spiders

Wolf spiders are readily identified by the pattern of eight eyes, al row of four small eyes in front below a pair of two large binocular eyes, with two small outward pointing eyes behind. Females usually build round silk egg sacks, which are carried about the fangs or attached to the spinnerets. The young are frequently seen riding about on the back of the female; after several days they wander off on their own. Wolf spiders have a reflective layer in their eyes, the tapetum, which will be visible at night as a sparkling point of blue-green light by flashlight. There are many wolf spiders in this area; four are quite common.

Arctosa littoralis: This medium sized dark gray spider is found under stream rocks in most of our local streams. Males and females are both about 1/2 inch long.

Pardosa sp.: Often present in huge numbers in leaf litter along the floor of our stream beds, the slender, 1/4 inch males have black front legs and pedipalps. These are used in a visual courtship display of the females. Adult females frequently are seen carrying a 1/8th inch diameter, somewhat lens-shaped, green-white egg sack. P. ramulosa and P. californica are common in yards; P. sierra is seen around our mountain streams.

Alopecosa kochi, Schizocosa mccooki Both of these species are locally common, usually around our woodlands and hillsides.

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Spider Control

Spiders may be controlled by the use of a fast acting poison with little residual activity sprayed directly on the offending animals. Ground running spiders are extremely chemosensitive and web building spiders seldom touch the substrate so direct contact with the spider may be necessary. Webs on shrubs and buildings are best controlled with regular hosing with a water stream, the spiders will usually rebuild their webs elsewhere. As most spiders are capable of "ballooning" or traveling with air currents on strands of fine unattached silk, complete control is essentially impossible. Young of black widows have been observed to completely reinfect an area within one week.

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The California common scorpion Paruoctonus sylvestrii has four dark stripes on its fairly heavy tail. Its pincers are slender and it is brown or tan in color. These scorpions are often found on rocky ground and open road cuts in our hilly areas.

The Arizona bark scorpion Centruroides exilicauda has been established in several very small populations in Orange County where they live under roof shingles and in palm tree leaves. These scorpions are the only truly dangerous scorpion in North America. They are about 3" in length, slender, reddish or tan in color with very thin, almost needle-like pincers and a slender tail.

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Armadillidium vulgare: The pillbug is completely ubiquitous everywhere European man has set foot. This isopod is capable of rolling into a ball when disturbed; only a few other rare local species can do this and these are mostly sea-shore or desert animals. It is commonly preyed on by Steatoda grossa (which may even be a specialist on them).

Porcellio sp. sow bugs: We have three species of these isopods. P. laevis is more common in moist areas and yards and is often numerous near streams. It tends to be smoother with more rounded front plates than P. dilatatum. P. dilatatum is perhaps slightly more common in dryer (but moist) areas and in gardens. It has a more granular, dry appearance with rearward projecting plates on the first segments.

P. scaber is occasionally found in our area near streams and in moist canyons, especially further up the coast. It is slightly more slender than P. laevis but otherwise similar.

Porcallionides pruinosus: These isopods have a powdery appearance and are smaller, more slender than Porcellio. They also tend to be slightly more active. Often seen in gardens alongside Porcellio and Armadillidium, they run rapidly with the body held higher. All of the above isopods (except perhaps P. scaber) tend to be common throughout our area and may all be found together in our area.

Ligia occidentalis is the common rock hopper or rock louse found on rocky shores along the coast. Some specimens can be over an inch in length and can run rapidly.

Ligidium gracilis is a small and very rarely seen isopod that can be found in wet leaf litter and stream-side soil in our mountain streams and in a few locations along the coast. It is much more common further north.

Several species of small isopods are common in marsh and beach debris along the coast; most in the genus Armadilloniscus.

Occasionally isopods are found which are bright blue in color. This is common in A. vulgaire, less so in Porcellio. The color is apparently due to a fungal infection.

Copyright (c) Blaine Hebert 1986
Permission is granted to reproduce this work for educational purposes.

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