A. CLASS ENTOGNATHA (all have recessed mouthparts)

1. PROTURA. Proturans are 0.6 to 1.5 mm. and white. They have no eyes, wings, or antennae. Their mouthparts are adapted for chewing or sucking. Their front legs resemble antennae as they are carried in an elevated position. Proturans are found in upper soil layers.

2. DIPLURA. Diplurans are 6 mm. or less and whitish in color. Their bodies have no scales. They have only two appendages at the end of their abdomen. They have chewing mouthparts. They have no compound eyes. Diplurans inhabit the soil and leaf mold and are commonly found under bark on the ground.

3. COLLEMBOLA (springtails). Collembolans are wingless. Their abdomens have up to six segments. There is an appendage, a collophore, on the ventral surface of the first abdominal segment and a furcula on the fourth abdominal segment. Springtails are found in the soil, in leaf litter, decaying wood, fungi, and near and on water.

B.    CLASS INSECTA: APTERYGOTA (primitive wingless insects)

4. THYSANURA (silverfish, bristletails, and rockhoppers). Thysanurans have chewing mouthparts. Their abdomens have between ten and eleven segments. It may look as if they have three tails, but these are a pair of lateral cerci and a caudal filament in the middle. Thysanurans can be found under rocks and bark, in leaf litter, and on their food sources: lichens, algae, mold, decaying fruit, and dead insects.

C. CLASS INSECTA: PTERYGOTA (winged insects)

5. EPHEMEROPTERA (mayflies). Mayflies have one or two pairs of wings. The front pair is large and triangular, the hind pair is smaller and rounded. The mouthparts are vestigial. Mayflies have filamentous cerci with two or three segments. Mayflies are found at streams and ponds.

6. ODONATA (dragonflies, damselflies, and skimmers). These insects have two pairs of net-veined, membranous wings. They have chewing mouthparts. Their heads are large, but their bodies are long and thin. They have very short antennae. They are found at streams and ponds.

7. ORTHOPTERA (grasshoppers, crickets, cockroaches, katydids, etc.).  Orthopterans are either wingless or have two pairs of wings. The front wings are parchment-like; the hind wings are membranous and fold like a fan when at rest. Mouthparts are chewing. 

Crickets (Gryllidae) are found under objects on the ground and on native vegetation (on which they feed).

Camel crickets (Gryllacrididae) are found in burrows in the ground.

Grasshoppers (Acrididae) are found in most habitats, especially in grassland communities.

Katydids (Tettigoniidae) are found in plants whose leaves they mimic.

Jerusalem crickets or potato bugs (Stenopelmatidae) are nocturnal. They burrow in the soil and feed on tubers and roots.

Cockroaches (Blattidae and Blatellidae) are found primarily in urban situations. However, locally the Western wood cockroach (Parcoblatta americana) may be found in old logs and under rocks in chaparral communities.

8. DERMAPTERA (earwigs). Earwigs have two pairs of wings, chewing mouthparts, and forceps-like cerci. They eat flowers and green vegetation near the ground, as well as dead insects.

9. ISOPTERA (termites). Termites are wingless or have two pairs of membranous, same-sized wings which are held flat over the abdomen when at rest. Termites have chewing mouthparts. The joint between the thorax and the abdomen is relatively broad. Termites are found in dead tree branches, buried posts or stumps, or in structural timbers.

10. EMBIOPTERA (webspinners). Webspinners have either no wings or two long, membranous pairs. Their mouthparts are chewing. They are found among grass roots, under rocks, and in leaf litter. They eat decaying vegetation.

11. PLECOPTERA (stoneflies). Stoneflies have two pairs of cross-veined wings. The front wings are narrow. The hind wings have a large anal lobe and are folded like a fan when at rest. Their chewing mouthparts are often reduced in size. They have long antennae and cerci. They are found at streamsides on vegetation or on rocks.

12. PSOCOPTERA (psocids, booklice, and barklice). Psocopterans have either no wings or two pairs. When wings are present, they are held over the body like a roof when at rest. Mouthparts are chewing. Antennae are slender. The clypeus protrudes on the face. They can be found in trees, on the trunks or foliage, under bark or rocks. They eat molds, pollen, and other organic matter.

13. MALLOPHAGA (chewing lice). Mallophagans are wingless. They have chewing mouthparts. Their triangular heads are as wide as or wider than their thorax. Their bodies are somewhat flattened. They have small eyes. They are ectoparasites of vertebrates, especially birds and mammals.

14. ANOPLURA (sucking lice). Anoplurans are wingless. Their mouthparts are adapted for piercing and sucking. Their heads are narrower than their thorax and are usually pointed in front. They have no eyes. They are ectoparasites of mammals.

15. THYSANOPTERA (thrips). Thrips are wingless or have two pairs of long, narrow, membranous wings that are fringed with long hairs. Their mouthparts are adapted to rasp and suck. Thrips parasitize plants. They can often be seen inside the veins of leaves, detected by holding the leaves up to the light.

16. HEMIPTERA (true bugs). Hemipterans are wingless or have two pairs of wings. The front pair of wings, called hemelytra, are thick and leathery at the base, but membranous away from the base. True bugs have piercing and sucking mouthparts that originate from the front of the head on the ventral surface. A shield-like scutellum is prominent between the wings at their base. True bugs are primarily herbivorous. A few true bugs prey on other insects or on mammal blood (ambush bugs, assasin bugs, and bedbugs). Many are found in or near water (water boatmen, water striders, backswimmers, and toe biters).

17. HOMOPTERA (bugs). Homopterans are wingless or have two pairs of membranous wings that have the same texture throughout. The wings are held like a roof over the body when at rest. The mouthparts are adapted for piercing and sucking and originate from the back of the head on the ventral surface. Bugs are herbivorous and are easily found on plants. Some of the more common bugs are aphids, scales, spittle bugs, mealybugs, cicadas, and leafhoppers.

18. NEUROPTERA (alderflies, lacewings, antlions, etc.). Neuropterans have two pairs of membranous, many-veined wings. The wings have similar size and shape and are held like a roof over the body when resting. Mouthparts are adapted for chewing. The antennae are long and have many segments. These insects are predaceous, many on other species of insects.

Dobsonflies (Corydalidae) and alderflies (Sialidae) are found at streamsides and ponds.

Snakeflies (Raphididae) can be found under loose bark.

Lacewings (Chrysopidae and Hemerobiidae) alight on plants.

Mantispids (Mantispidae) are nocturnal and can be found near the nests of bees and wasps.

Antlions (Myrmeleontidae) burrow in the uppermost layers of sandy, dry soil, awaiting their prey.

19. COLEOPTERA (beetles). This is the largest order of insects. Beetles usually have two pairs of wings. The fore wings (called elytra) are hard and thick and meet in a straight line down the back when at rest. When present, the hind wings are membranous and used for flight. At rest, they fold beneath the elytra. Some beetles have only elytra or have reduced, flightless hind wings. Some beetles are entirely wingless. They have chewing mouthparts. There are so many different beetles that nearly every habitat is home to some species.

Anobiid beetles (Anobiidae) can be found in galls or in dead branches.

Wood borers (Bostrichidae) burrow in dried wood (dead or burned limbs).

Many buprestid beetles (Buprestidae) eat pollen.

Soldier beetles (Cantharidae) can be found on vegetation by day.

Predaceous ground beetles (Carabidae) are nocturnal, but can be found under rocks or logs by day, especially in moist areas.

Longhorn beetles (Cerambycidae) are often found at flowers where they eat pollen and other plant parts.

Leaf beetles (Chrysomelidae) mostly feed on leaves, a few on aquatic plants.

Tiger beetles (Cicindelidae) are predaceous and stalk their prey on the ground.

Ladybugs or ladybird beetles (Coccinellidae) prey on soft-bodied insects like aphids, mealybugs, and mites.

Snout beetles or weevils (Curculionidae) are commonly found boring into plant materials - acorns, flower buds, grain. The Yucca weevil (Scyphophorus yuccae) is found at the base of Yucca whipplei.

Carpet beetles (Dermestidae) are scavengers and are found on animals and plants, in stored grain, or in wasp nests.

Predaceous water beetles (Dytiscidae), whirligig beetles (Gyrinidae), and scavenger water beetles (Hydrophilidae) are found in ponds and streams.

Click beetles (Elateridae) are herbivorous.

Blister beetles (Meloidae) are herbivorous, and many are partial to flowers.

Glowworms (Phengodidae) are nocturnal.

Water pennies (Psephenidae) attach themselves to rocks or vegetation in streams.

Scarab beetles (Scarabaeidae) are commonly found on the plants that they eat.

Carrion beetles (Silphidae) are found primarily on carrion.

Rove beetles (Staphylinidae) are commonly found in or around carcasses, dung, in fungi, or at streamsides in decaying vegetation.

Darkling ground beetles (Tenebrionidae) are commonly found under bark or debris.

20. MECOPTERA (scorpionflies). Scorpionflies may be wingless or two-winged. Their wings are long, narrow, and net-veined. Their mouthparts are chewing and are located at the tip of a long, deflexed beak. The last abdominal segments may be curved upward, like a scorpion. Scorpionflies are insectivorous and are common on grassy hillsides and in chaparral.

21. TRICHOPTERA (caddisflies). Caddisflies have two pairs of membranous, hairy wings. The wings are held roof-like over the body when at rest. The mouthparts are usually vestigial, but may be adapted for chewing or licking liquids. Caddisflies are found near water where their aquatic larvae build elaborate fixed or movable cases (retreats or homes) with their silk and grains of sand, pieces of leaves, tiny sticks, or other objects.

22. LEPIDOPTERA (butterflies and moths). Lepidopterans usually have two pairs of wings. The wings are membranous and, along with the body, are covered with overlapping scales. The coiled proboscis is adapted for sucking. Adults feed on nectar, other plant secretions, honeydew, and water, as well as rotting matter.

Butterflies tend to fly by day. The terminal portion of their antennae is knob- or club-shaped. Their fore and hind wings overlap, but are not attached. Butterflies tend to be brightly colored.

Moths are more commonly seen by night. Their antennae are feathery, sawtoothed, or threadlike, and are not clubbed. In many moths, the fore and hind wings are attached. A bristle or series of bristles (called a frenulum) on base of the hind wing hooks onto a flap or tuft of scales (the retinaculum) on the underside of the fore wing.

Yucca and longhorn moths (Incurvariidae) are usually day-flying. The California Yucca moth (Tegeticula maculata, Incurvariidae) is the only pollinator for Yucca whipplei. Females oviposit in the flower then carry pollen to the stigma. When the larvae emerge, they eat only a portion of the seed in each pod. This is their only food.

Tortricid moths (Torticidae) are usually night-flying. Their caterpillars are leaf-rollers and feed on a wide variety of plants.

Plume moths (Pterophoridae) are primarily nocturnal. They take their name from their feathery hind wings. Many plume moth larvae bore into bark or buds. Others eat a variety of leaves.

Snout or grass moths (Pyralidae) can be recognized easily by their triangular fore wings and snout-like palpi. They comprise a diverse group with some feeding on leaves, fungi, or mosses, others boring into roots, scavenging, or preying on other insects. One subfamily is aquatic; its larvae feed on submerged plants.

Measuring, looper, or inch worms (Geometridae). These moths have slender bodies. Their fore wings are often decorated with wavy lines. They are primarily nocturnal. The oak winter highflier (Hydriomena nubilofasciata) is one of the most common defoliators of coast live oak (Quercus agrifolia) and other oaks (Quercus spp.). Other species may be found on Ceanothus spp., buckwheats (Eriogonum spp.), and toyon (Heteromeles arbutifolia).

Giant silk moths and royal moths (Saturniidae)

are often about at dusk feeding on nectar. They have a long proboscis. They have a thick, heavy body with long, narrow fore wings. The Ceanothus silk moth (Hyalophora euryalus) is very common locally and found on California lilac (Ceanothus spp.), coffeeberry (Rhamnus californica), willows (Salix spp.), and other shrubs. The Polyphemus moth (Antheraea polyphemus) is also common and is found in broadleafed trees and shrubs, as well as stonefruit trees.

Sphinx, hawk, and hummingbird moths (Sphingidae) are medium to large with streamlined, but stout bodies. Their fore wings are elongated and have a strongly oblique outer margin. Their antennae are knobbed and then tapered toward the tip. Males have a very long tongue (two to three times their body length). They feed in deep-throated flowers and are important pollinators for some plants. Most are nocturnal. They can be found around a variety of plants including manzanita (Arctostaphylos spp.), shrubs in the Rosaceae, willow (Salix spp.), snowberry (Symphoricarpos spp.), and low-growing herbs.

Oak moths (Notodontidae) are stout moths covered in scales and hairs. They are nocturnal. They can be found in oaks (Quercus spp.).

Tiger moths and wasp moths (Arctiidae) are stout, furry moths. They are often brightly colored. Antennae are feathery in males, filamentous in females. Most species are nocturnal. They may be found on lichens, rocks, bark, oaks, and low-growing herbs.

Noctuid, owlet, and cutworm (Noctuidae) moths are also stout-bodied. Their fore wings are narrow, and their hind wings are fan-shaped. The wings are cryptically colored. Most are nocturnal. They are common in and near fields and orchards.

Swallowtails and parnassians (Papilionidae) are some of the showiest butterflies. Most are large and brightly colored. Swallowtails have "tails" on their hind wings. The Anise swallowtail (Papilio zelicaon) is found on sweet fennel (Foeniculum vulgare) and other members of the Apiaceae.

Whites, sulfurs, and orangetips (Pieridae) are medium-sized butterflies. They are yellow or white with black markings. They are strong fliers and inhabit open areas. Many feed on mustards (Brassicaceae) or plants in the pea family (Fabaceae). The cabbage butterfly (Pieris rapae) feeds on cultivated and weedy plants in the Brassicaceae. The California dogface (Colias eurydice) is the official California State butterfly. It is found on false indigo (Amorpha californica) and other low-growing plants. The Alfalfa sulfur (Colias eurytheme) is found in alfalfa fields, as well as natural and ruderal open areas.

Coppers, hairstreaks, metalmarks, and blues (Lycaenidae) are small butterflies with metallic blue, coppery, orange, or gray wings. The undersides of the wings are usually different colors from the upper surface. The antennae are often ringed in white. Most have a very specific food source such as Dudleya lanceolata and other species of Dudleya, buckwheats (Eriogonum spp.), deerweed (Lotus scoparius), dock (Rumex spp.), and mistletoe (Viscaceae). Some are listed as sensitive species.

Satyrs and woodnymphs (Satyridae) are medium-sized butterflies. They tend to be brown and whitish. Their wings have rounded margins. Most are dark with eyelike spots, at least on the undersides. Their wings are closed at rest. Their flight pattern is somewhat bouncy, and they often land on the ground for shelter. They are common in grasses.

Brush-footed, fritillaries, checkerspots, mourning cloaks, and admirals (Nymphalidae). Brush-footed butterflies are so named because their fore legs are reduced in size and bear long hairs. They have broad wings and are strong fliers, often flying long distances. They are found on many flowering plants. Monarch butterfly (Danaus plexippus) larvae feed on milkweed (Asclepias spp.). Adults are found on willows (Salix spp.), Eucalyptus spp., Ceanothus spp., and other shrubs. Chalcedon or common checkerspot (Euphydryas chalcedona) larvae feed on sticky monkeyflower (Mimulus aurantiacus) and other figworts (Scrophulariaceae). The mourning cloak (Nymphalis antiopa) is found on willow (Salix spp.). Painted lady (Vanessa cardui) is found on thistles (Cirsium spp.), mallows (Malva spp.), and other low-growing plants. The California sister (Adelpha bredowi) is found in oaks. Buckeye (Junonia coenia) is found on plantain (Plantago spp.) and figworts (Scrophulariaceae). Other butterflies in this family may be found on nettles (Urtica holosericea), Ceanothus, or willow (Salix spp.).

Skippers (Hesperiidae) are stout-bodied. They have short wings and large heads. Their common name comes from their flight pattern which is strong, but jerky. At rest, their wings are spread out laterally. They can be found in grasses and among mallows (Malva spp.)

23. DIPTERA (Craneflies, gnats, midges, mosquitoes, and flies) have one pair of wings and a second pair that has been modified into knobby structures called halteres. Some species do not have the wings, but do have halteres. The wings are membranous and usually transparent. Mouthparts are adapted for lapping, sponging, or piercing and sucking liquids. In the suborder Nematocera (craneflies, gnats, midges,  and mosquitoes) the legs are long and slender, and the antennae are long and with many similar segments. In the suborder Brachycera (flies) the legs are short and stout, and the antennae are short with one or more segments very different from the others.

Craneflies (Tipulidae) are commonly found in damp places (decaying vegetation, rotting logs, streamsides, next to ponds, and on mosses) and grasses.

Gnats (Sciaridae) are also found in moist places (decaying vegetation and fungi).

Gall midges (Cecidomyidae). Larvae may feed on decaying vegetation or fungi. Others are predaceous on mites and small insects. Some form galls by boring into California sagebrush (Artemisia californica) and prickly pear cactus (Opuntia spp.).

Black flies (Simuliidae) are common near streams on rocks.

Moth flies (Psychodidae) are found in streams on boulders, logs, and overhanging vegetation.

Mosquitoes (Culicidae) can be found near clear standing water and pools.

Water midges (Chironomidae) are found near streams, ponds, and mud.

Soldier flies (Stratiomyidae) frequent flowers and wet places on vegetation.

Horse flies (Tabanidae) can be found near large mammals, especially horses.

Robber flies (Asilidae) are found in many habitats and prey on other insects.

Bee flies (Bombyliidae) also are in many habitats, but are most common in sunny areas with lots of wildflowers.

Hover flies (Syrphidae) are generalists, but also are common near flowers.

Fruit flies (Tephritidae) and common in chaparral and coastal scrub communities.

Vinegar or trail flies (Drosophilidae) are found on trails near streams (and often are pesky, flitting about hikers' eyes).

Muscid flies (Muscidae) are common in meadows and pastures near dung, animals, and humans.

Blow flies (Calliphoridae) are found in flowers, near fresh dung, and near dead animals.

Flesh flies (Sarcophagidae) frequent flowers. They can also be found on the ground in dry, rocky areas. They often land on one's skin in search of moisture.

Tachinid flies (Tachinidae) feed on nectar and other exudates of plant and are found near flowers and low-growing vegetation.

Louse flies (Hippoboscidae) are parasites of birds and mammals, sucking their blood.

24. SIPHONAPTERA (Fleas) are wingless parasites with laterally compressed bodies and jumping hind legs. They are parasitic on birds and mammals, sucking their blood.

25. HYMENOPTERA (Bees, wasps, and ants) have two pairs of membranous wings or are wingless. Their mouthparts are adapted for biting. The abdomen is often very constricted ("wasp-waisted"). Many species are parasitic in the larval stage, and the ovipositor is adapted for sawing or piercing so the female can oviposit into the tissues of plants or other insects. In many species, the ovipositor is adapted for stinging. Besides parasitic species, there are others that are herbivorous, insectivorous, or eat pollen. Many species are colonial.

Sawflies (Tenthredinidae) can be found near willows (Salix spp.) and other broadleafed shrubs, as well as ferns.

Braconid wasps (Braconidae) are parasitoids as larvae, particularly in Lepidoptera larvae, and some parasitize Diptera, Coleoptera, and aphids.

Ichneumonids (Ichneumonidae) are parasites of other insects and other arthropods. They are day-fliers.

Velvet ants (Mutillidae) have a dense hairy covering. Females are wingless. Some are nocturnal. They have a powerful sting. They are found on the ground, especially in sandy places.

Ants (Formicidae) have elbowed antennae and an accentuated narrowing between the thorax and abdomen. The head is broader than the thorax, and the abdomen is relatively enlarged. Ants are colonial. Some are parasitic, some carnivorous, while others eat honeydew excreted by lycaenid butterflies larvae, aphids, and scale insects. Others feed on fungi. Many give a painful bite as well as sting, others sting only.

Yellowjackets, hornets, and paper nest wasps (Vespidae) often prey on caterpillars.

Digger wasps or thread-waisted wasps (Sphecidae) can be thread-waisted or stout-bodied. They prey on other insects and spiders.

Cuckoo and carpenter bees (Anthophoridae). The California carpenter bee (Xylocopa californica) can be found in the dry stalks of Yucca whipplei where it nests.

Bumble bees and honey bees (Apidae) are found in or near a variety of flowers and harvest nectar and pollen. Clover and alfalfa are frequented by bumble bees (which have relatively long tongues). Honey bees (with their shorter tongues) visit a variety of smaller flowers.