| Arachnids | (Spiders, Mites, Scorpions) | |
| Common Scorpion | 1.25", sting is painful | |
| Burrowing Scorpion | 2.5", ambushes prey from burrow | |
| Sun Spider (Wind scorpion) | Hairy nocturnal no stinger | |
| Daddy Long-legs | Not true spider, no fangs doesn't bite | |
| Sow Bug Killer Spider | No web, kills Sow & Pill Bugs | |
| Western Black Widow Spider | Venom is a neurotoxin | |
| Mouse Spider | 1/4", dull brown | |
| Orb Web Weaver Spider | Web is wheel shaped | |
| Jeweled Araneus Spider | Spins loose orb web up to 6' | |
| Trash-web Spider | Weaves a composite web | |
| Jumping Spider | Can jump some distance | |
| Green Lynx Spider | Large body of 3/4", no web | |
| Crab Spider | Has no web, crab-like appearance | |
| Spider Mite | Spin fine silken carpets under leaves | |
| Velvet Mite | Inhabits the soil, large, 1/4", bright red | |
| Pacific Coast Tick | Feeds on blood of vertebrates | |
| Centipedes | ||
| Multicolored Centipede | 3 to 4", bite can be painful | |
| Millipedes | ||
| Hiltonius Millipede | Prefer moist conditions, 3" | |
| Crustaceans | ||
| Common Pill Bug | Rolls into a tight ball when disturbed | |
| Dooryard Sow Bug | Larger than pill bug, can't roll up | |
| Insects | ||
| Order Colembola | Snaps tail-like appendage to move | |
| Leaf Litter Springtail | 1/8" | |
| Dung Springtail | 1/8" | |
| California Springtail | 1/8" | |
| Common Springtail | 1/8" | |
| Order Thysanura | ||
| Long Tailed Silverfish | Covered with shiny, slick scales | |
| Bristletail | Nocturnal, abhor light like silverfish | |
| Order Ephemeroptera | Immature forms are aquatic | |
| Mayfly | ||
| Order Odonata | Immature forms are aquatic | |
| Pastel Skimmer Dragonfly | 1.75" | |
| Big Red Skimmer Dragonfly | 2.5", orange-red | |
| Common Green Darner Dragonfly | Large, 3.25" | |
| Multicolored Darner Dragonfly | 2.5", blue & black | |
| Violet Dancer Damselfly | 1 to 2", intense blue | |
| Order Dermaptera | Pincers weak & mostly harmless | |
| European Earwig ● | 0.75", females care for young | |
| Ring-legged Earwig ● | 0.75", also from Europe | |
| Maritime Earwig | ||
| Order Orthoptera | ||
| Chaparral Katydid | Pallid Band-wing Grasshopper | 1.5" |
| Clear Winged Grasshopper | ||
| Gray Bird Grasshopper | Females to 2.5" | |
| Tree Cricket | 0.5", live in trees and shrubs | |
| Field Cricket | 0.5 to 1.25", black or brown | |
| Jerusalem Cricket | Large, 2" with bald head, nocturnal | |
| California Camel Cricket | Secretive, hump backed | |
| Sand Roach | Found in coastal dunes | |
| Western Wood Roach | Found in sage & chaparral | |
| Minor Ground Mantis | 1.25", carnivore, run on ground | |
| Order Isoptera | Live in colonies | |
| Western Subterranean Termite | Swarms in the fall | |
| Western Drywood Termite | No ground contact needed | |
| Pacific Dampwood Termite | Likes buried wood | |
| Order Hemiptera | ||
| Closterocoris amoenus | Nymphs are ant mimics | |
| Lopidea nigridia | Feeds on silver dune lupine | Say's Stink Bug | Produces a strong acrid smell |
| Harlequin Bug | Eats Brassicacaea species, also stinks | |
| Leafhopper Assassin Bug | Preys on insects | |
| Milkweed Assassin Bug | Preys on insects | |
| Ringed Assassin Bug | Preys on insects | |
| Bordered Plant Bug | Can congregate in large numbers | |
| Bee Assassin | Preys on ants, bees, and beetles | |
| Order Homoptera | ||
| Blue-green Leaf Hopper | 1/4", iridescent | |
| Spittlebug | Nymphs hide in spit on ceanothus and baccharis | |
| Treehopper | Looks like a thorn or ridge on a branch | |
| Aphid | Often "raised" by ants | |
| Order Neuroptera | ||
| Snakefly | Long prothorax and head are snake-like | |
| Green Lacewing | Go to light at night, larvae eat aphids | |
| Brown Lacewing | Wings covered by micro bristles | |
| Antlion (Doodlebug) | Larvae dig pits to trap ants | |
| Order Coleoptera | Thickened hard fore wings | |
| Groundselbush Beetle | iridescent larvae and adult | |
| Black Ground Beetle | 5/8", long-legged, fast-running | |
| Snail Eater Ground Beetle | Prey on slugs, snails | |
| Tiger Beetle | Live in moist sand near water, eat insects | |
| Ten-lined June beetle | Makes a hissing noise when handled | |
| Rove Beetle | Short wing covers | |
| Tumbling flower beetle | Short wing covers and a pointy tail | |
| Blister Beetle | Contain cantharidin causing skin blisters | |
| Click Beetle | Makes an audible clicking sound | |
| Western Spotted Cucumber Beetle | 1/4" | |
| Ladybird Beetle | Voracious predator of aphids & scale | |
| Subterranean Dune Beetle | ||
| Wooly Ground Beetle | Wooly reddish-brown hairs | |
| Darkling Ground Beetle | ||
| Iron Clad Beetle | Hard body, found under oaks | |
| Scarab Beetle | Antennae with a club of leaf-like plates | |
| Order Hymenoptera | ||
| California Harvester Ant | Large, red, stings, vegetarian | |
| Pyramid ants | Small,black with brown jaws | |
| Carpenter Ant | Large, black & red, stings | |
| Paper Wasp | Makes paper mache-like nest | |
| Live Oak Gall Fly (wasp) | Forms galls on Oaks | |
| Spider Wasp | Stings, preys on spiders | |
| Sand Wasp | Also known as digger wasps | |
| Ichnumen Wasp | Solitary wasp | |
| Velvet Ant | Stings, female is wingless | |
| Hornet | Protective of nest, stings if disturbed | |
| Yellow Jacket | Stings, attracted to meat & fruit | |
| Burrowing Bee | Nest is constructed in a sand bank | |
| Sweat Bee | Solitary bee | |
| Honey Bee | Stings, but not easily provoked | |
| Bumble Bee | Stings, but not easily provoked | |
| Order Diptera | ||
| Common Crane Fly | Often mistaken for giant mosquito | |
| Giant Crane Fly | Body 1.3", wing span 3" | |
| Mosquito | Buzz is high-frequency vibration of wings | |
| March Fly | 1/4", poor fliers, scavengers of decay | |
| Wooly Sagebrush Gall midge | Makes wooly galls on sagebrush | |
| Horse Fly | Female bite painful, breed in aquatic habitat | |
| Robber Fly | Hunts other flys | |
| Flower Fly | Hover about flowers, destroy aphids | |
| Deer Louse Fly | Ectoparasites of deer, sucks blood | |
| Bee Fly | Look/act like bees, feed on nectar | |
| Hover Fly | ||
| Common House Fly | Regurgitation leaves fly specks | |
| Tachinid Fly | Have stiff bristles, parasitize cutworms | |
| Green Bottle Fly | Infest garbage & fresh dog feces | |
| Sarcophagid Fly | Deposit live maggots instead of eggs |