A number of interesting insects can be observed at Quail Ridge, mostly in the spring. Some of the more conspicuous include:

Vanessa annabella; Photo courtesy  of T. W. Davies © California Academy of SciencesButterflies: Among the most colorful and easily seen insects at Quail Ridge are the pipevine swallowtail butterfly (Battus philenor), whose larvae feed on pipevine (Aristolochia californica), the chalcedon checkerspot butterfly (Euphydryas chalcedona), whose caterpillars are common on bush monkeyflower (Mimulus aurantiacus), and the California sister butterfly (Adelpha bredowii), whose larvae feed on oaks (Quercus spp.). Early in spring you can see the brightly colored, spiky (but not hairy) caterpillars on their host plants. Later in spring the even-more-brilliant adults can be observed nectaring at buckeye trees (Aesculus californica) and other plants. The mass emergence of adult pipevine swallowtails in April is a truly spectacular sight.

Butterflies are the one group of insects you can easily identify to species using a field guide, such as A Field Guide to Western Butterflies48 or Butterflies of North America43. Additionally, the Quail Ridge butterfly list is essentially complete. Bill Patterson and Greg Kareofelas‘s observations of the 66 butterfly species at the Reserve, including what plants the caterpillars feed on and what time of year the adults are active, comprise this infomative list.

Western Tussock Moth; Photo courtesy of T. W. Davies © California Academy of SciencesMoths: The list of moths collected by Greg Kareofelas and Bill Patterson at Quail Ridge continues to grow every year. Most of the species are inconspicuous both as caterpillars and adults, but caterpillars of several species are sometimes seen in large numbers devouring the foliage of oaks in spring. During outbreak years for the Pacific tent caterpillar (Malacosoma constrictum, Lasiocampidae), you may see hundreds of reddish-brown, hairy caterpillars eating oak leaves or crawling on the ground beneath trees. The fruit-tree leaf-roller (Archips argyrospilus columbiana, Tortricidae) also sometimes has huge outbreaks on the blue oaks at Quail Ridge. Other oak defoliators that are common in the region, but have not been seen often at Quail Ridge, are the California oakmoth (Phryganidia californica, Dioptidae), which has hairless large-headed caterpillars, and the western tussock moth (Orgyia vetusta, Lymantriidae), whose caterpillars have a row of white “hairbrushes” down their backs.

Bumbus californicus; Photo courtesy of Tom Greer © 2004 Tom GreerBees: There are at least 40 species of bees at Quail Ridge (see bee list). Most are natives except for the familiar European honey bee, Apis mellifera, a generalist flower visitor, and a medium-sized leafcutting bee, Megachile apicalis, from the Mediterranean area, a specialist on the invasive weed yellow starthistle (Centaurea solstitialis). Most of our native bees are solitary ground-nesting species, except for the large, fuzzy, colorful bumblebees, Bombus spp., which live in colonies.

In early spring, large bees may be heard buzzing loudly around manzanita (Arctostaphylos manzanita) shrubs in flower. The large fuzzy gray Habropoda depressa, and queens of the yellow-and-black striped Bombus melanopygus, are among those you may see quickly sipping nectar from the bell-shaped white flowers. On buttercup (Ranunculus californicus) flowers, you can see males and females of the solitary ground-nesting Andrena caerulea, which specializes on buttercup pollen to feed its young. They are slender and dark metallic bluish-green, and about half as long as the diameter of the flower. Males are smaller and more slender than females and have white hairs on their faces. Females gather pollen into special brushes on their hind legs that appear to get larger and more yellow as they accumulate pollen. On redbud (Cercis occidentalis), you can observe honeybees, bumblebees, and a variety of native solitary bees. The solitary bees include the blue orchard bee, Osmia lignaria propinqua, a honeybee-sized metallic blue species that is available commercially for pollination of orchard and other crops. Smaller bees belonging to the sweat bee family (e.g. Halictus, Evylaeus, Dialictus) glean pollen from redbud flowers that have been opened by larger bees.

Ants: There are probably about 40 species of ants at Quail Ridge. Easily seen species include: the seed harvester Messor andrei, a large black ant whose nest entrances are typically decorated with large piles of seed chaff; the velvety tree ant Liometopum occidentale, an orange and gray species that forms large foraging lines on the trunks of oak trees; and the carpenter ant Camponotus semitestaceus, a very large red and black species that makes conspicuous crater-shaped nest entrances on the ground.

Other notable species are the army ant, Neivamyrmex nigrescens, a nocturnal marauder that attacks other ant colonies, and Pseudomyrmex apache, a bright-orange species that lives and forages on manzanita shrubs. Both of these species are among the northernmost representatives of tropical groups. Manzanita (Arctostaphylos manzanita) is a key plant species for Pseudomyrmex and other arboreal ants because older plants have abundant cavity-riddled dead wood that provides nest sites for ants, adjacent to live wood that provides moisture.

Gall wasps: Galls are modifications of plant growth induced by other organisms. The oak species at Quail Ridge provide many fine examples of twig and leaf galls caused by wasps of the family Cynipidae. The galls of each wasp species are distinctively different. The most familiar one is the oak apple gall, a large smooth gall found on valley oaks (Quercus lobata), caused by the tiny cynipid wasp Andricus quercuscalifornicus. The cynipid wasp Antron douglasii induces two types of galls on valley oaks and blue oaks (Q. douglasii): pink spiny turbans in summer, and white berry-like ones in early spring. Other galls range from simple woody swellings to exotic shapes like artichokes or sea urchins. Moreover, each kind of gall supports a small community of parasites and other dwellers, usually other kinds of wasps, that are specialized to live in the gall of a particular cynipid species. See the Fremontia articles by Russo51 and Schick52 for more about the fascinating ecology of Californian oak galls. A good comprehensive reference is Russo’s Plant Galls of the California Region50.

Aquatic insects: The man-made stockponds on Quail Ridge contain complex communities of native aquatic insects. Ten-spot skimmer Dragonfly; Photo courtesy of Gerald and Buff Corsi © California Academy of SciencesThese include many beetles (e.g. Dytiscidae, Hydrophillidae), dragonflies and damselflies (e.g. Coenagrionidae, Libellulidae, Aeshnidae), Mayflies, true bugs (e.g. Bellostomatidae, Corixidae, Gerridae, Notonectidae), and others. One of the most impressive of the pond residents is the 7 cm long giant water bug, Lethocerus americanus. Herpetologist Mike Benard has seen this voracious bug eat the tadpoles and adults of the Pacific treefrog, Hyla regilla, a rare example of an invertebrate preying on (as opposed to parasitizing) a vertebrate (see the header)! Look in the stock ponds to see what other aquatic insects you can find.

There are also several streams on the Reserve. These are largely ephemeral, but contain many interesting groups of insects. In the winter through early summer, large numbers of water striders (Gerridae) fill the many pools of the stream. Also in the stream are aeshnid dragonfly nymphs, which possibly prey on the newt larvae that share the pools with them. Other notable residents of the streams are dobsonflies (Corydalidae), large Dipteran larvae, and club-tailed dragonflies (Gomphidae).

Photo Credits: Title, Giant Water Bug (Mike Benard),Vanessa annabella and Western Tussock Moth (T. W. Davies), Bumbus californicus (Tom Greer), Ten-spot skimmer dragonfly (Gerald and Buff Corsi). For more pictures see:

This page last updated: June 23, 2005  

Contact: Dr. Virginia Boucher
John Muir Institute of the Environment
109 The Barn, University of California, Davis, CA 95616
Phone: 530-752-6949; email:

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