Home A - Z FAQ Art Prints Online Library Discussion Forum Muir Weather Maps About Search
Online Library: Title Author California Geology History Indians Muir Mountaineering Nature Management

Insects of Yosemite National Park

Handbook of Yosemite National Park (1921)
by Edwin C. Van Dyke

Next: Trees of YosemiteContentsPrevious: Fishes of Yosemite

Insects of Yosemite National Park


By Edwin C. Van Dyke

Assistant Professor of Entomology, University of

To the uninitiated the word "insect" conjurs all kinds of creepy crawly "bugs"—yet to those who are at all interested in Nature, the study of entomology is a most fascinating one. The insect fauna of Yosemite National Park is especially rich and offers an excellent field to collectors. [Editor’s note: collecting is not allowed within Yosemite National Park.—DEA] Indeed, so numerous are the species that many will be noticed by even the most casual observer. The Nature-lover will be most at tracted by the multi-colored butterflies, the day flying moths, the bronze and gold timber beetles, and such other insects as are beautiful in form and have interesting habits. To the naturalist all of the insect life will be attractive and he will be kept busy, for the region possesses a most wonderful assemblage of forms. Even the most prosaic individual must needs take notice, for the thirsty mosquito or deer fly will sooner or later tax him for a meal and the sociable ant will always be ready to welcome him.

The butterflies and moths, which belong to the order Lepidoptera, are generally the first to claim attention. Some of the former will be seen in the park no matter where one wanders. In the meadows there will be the ever present sulphur butterfly (Colias eurytheme Boisd.) and numerous busy skippers, as well as an occasional large orange-red fritellary or silver spot, so named from the numerous silvery patches on the under side of the wings. The largest of our mountain fritellaries is leto (Argynnis leto Behr. Plate xvi, 9), a noble insect with a wing expanse of about three inches, but the commonest is Behr’s fritellary (Argynnis monticola Behr.), a somewhat smaller species. About damp patches along the roadside or at the sandy margins of streams great congregations of butterflies may often be seen, all eagerly quenching their thirst. The dominant species here will generally be the California tortoise shell (Vanessa californica Behr.) which is of a rich red color above and dark, almost black, beneath. This insect is always abundant in the mountains. Some years its larvae have been so numerous that they have become serious pests, defoliating the deer brush and other species of wild lilac over extensive areas. Other butterflies often found drinking are numerous species of blues and a sprinkling of white admirals (Basilarchia lorquini Boisd.). The latter is a moderate-sized, black butterfly with red tips to the wings. A somewhat larger butterfly which simulates it in color pattern is Adelpha bredowii var. californica But. (Plate xvi, 4). Of the several swallowtails the commonest is the dark yellow tiger swallowtail (Papilio rutulus Boisd.). Less common is its creamy colored cousin, Papilio eurymedon Boisd., and the prize of all is the two-tailed swallowtail. (Papilio daunus Boisd. Plate xvi, 1) which is a rare visitor.

As one leaves the Valley and enters the high country other butterflies will be noticed. One of these, Parnassius clodius Menetr. (Plate xvi, 11), is truly a butterfly of the high mountains. It is of fair size, white, with several short black bars on the forewings and a few pink spots on the hind, and with much of the wing membrane uncovered by scales. One most often sees it flying about the higher mountain meadows or beneath such scattered trees as occur in the alpine forests. One may at times notice flying about the yellow pines numbers of the pine white (Neophasia menapia Feld. Plate xvi, 8). Its distinguishing characteristic is the pinkish outlining to the veins on the underside of the wings. The caterpillars of this species often greatly injure the pines through defoliation. At the tops of the various domes and at other exposed lookout places two more whites (Pieris sisymbri Boisd. and Pieris occidentalis Reak.) may generally be seen on sunny days. These prominent places are, in fact, favorite congregating spots for many types of insects besides the butterflies. Lazily sailing across the valleys we are almost sure to see our well-known friend from the lowlands, the monarch or milkweed butterfly (Anosia plexippus Linn.). This large red butterfly wanders far and wide during the summer months in search of the food plant for its young, the various species of milkweed, but in late autumn it migrates to the coast to one or the other of its numerous assembling grounds where it spends the winter. The highly prized black alpine swallowtail (Papilio indra Reakirt. Plate xvi, 6) may also greet one’s vision as it soars away from its rocky heights.

Mountaineers will probably be familiar with our three most common high-mountain species. The brilliant little copper (Chrysophanus cupreus Edw. Plate xvi, 3) may often be seen basking in sunny spots in Tuolumne Meadows. Behr’s sulphur (Colais behri Edw. Plate xvi, 5), a rather small greenish yellow butterfly, which haunts the most alpine meadows and grassy slopes, is a southern remnant or relict of an arctic race left stranded and isolated in our southern Sierra. That hardy gray satyr of the heights, (Aeneis ivallda Mead. (Plate xvi, 7), can only be found about the crags and high rocky slopes where it flies freely from place to place when the weather is pleasant but instantly settles when it is otherwise, and because of the harmony of its colors with the surroundings disappears from view. Even this habit does not always protect it, for many a specimen has been caught up by a mountain storm and left to perish high up on the snowfields and glaciers.

Of the moths there are even more species to be found than there are of the butterflies, but the most are of somber appearance or so small that they will rarely attract the notice of any but the expert. of the more conspicuous several are day-flying like the showy orange and black "sheep moth" (Pseudohazis eglanterina Boisd. Plate xvi, 10). This flies throughout the chaparral areas of the Sierra and as a result may often be seen about the lower ridges and lesser peaks. Its larvae when fully grown are several inches long and black, armed with prickly yellow spines. They feed on the willow and several of the chaparral shrubs. Another day-flying moth is the wild forget-me-not moth (Gnophaela latipennis Boisd. Plate xvi, 2), a beautiful black species maculated with yellow. Whenever one can locate a patch of its food plant at higher levels it can generally be found. The most conspicuous of the night-flying moths is the large California silk moth (Samia rubra Behr.), a moth with a wing expanse of several inches and with a brick

Some butterflies and moths of Yosemite National Park
Some Butterflies and Moths of Yosemite National
red color. This species in its earlier stage feeds on various shrubs, chiefly the pigeon berry or cascara, and as an adult may often be attracted to light. The most important moth in the park, however, from the standpoint of destructiveness is a very diminutive one. It is the lodgepole pine or "tamarack" needle miner (Recurvaria milleri Busck.), so called from the fact that its larvae tunnel the terminals. of the needles of this common pine of the higher altitudes. This kills the needles, thus weakening the trees so that they fall an easy prey to the attacks of the destructive bark beetles. The great areas of dead "tamaracks" or lodgepole pines which one sees in the mid-Sierran region bear mute testimony to the destructiveness of this insect.

After the moths and butterflies, the beetles or Coleoptera provide us with the greatest number of showy representatives. Among the conspicuous species of this order in the park are a number of the long-horned wood boring beetles of the family Cerambycidae. One of these, the elderberry beetle (Desmocerus auripennis Chev. Plate xvii, 4), is often to be seen resting on the leaves of its food plant. It is a large bluish-black beetle with wing cases entirely red if a male or blue bordered with red if a female. Another is the maculated timberman (Monohammus maculosus Lec. Plate xvii, 7), a large black and white clouded beetle which may often be found resting on the sticks of corded pine wood or stretched out along the protected portion of an old log. When isolated from its environment this is a very conspicuous insect, but when at rest on the side of an old log, it so thoroughly blends with its surroundings that it is hard to detect. A most interesting and peculiar long-horned beetle is Ulochaetes leoninus Lec. (Plate xvii, 8), a good-sized and somewhat hairy black and yellow barred beetle which has its wing causes so very much abbreviated that the greater portion of the wings are exposed to view even when folded. This species haunts the dead yellow and Jeffrey pines. On milkweed plants another very conspicuous member of the family may be seen. It is the so-called milkweed beetle (Tetraopes femoratus var. basalis Lec.) which is of a bright red color spotted with black. Many of the beetles of this family are pollen feeders, and such flowers as the wild lilac and wild hellebore are especially attractive to them. Here many of the wasplike members of the great genus Leptura (Plate xvii, 18) may be found. Even at night one may collect some of these beetles for many are nocturnal and often fly to lights. Two of the largest are Ergates spiculatus Lec. (Plate xvii, 17) and Prionus Californicus Mots. (Plate xvii, 15), the former over two inches in length and the latter an inch and a half and both of a reddish-brown color.

Another group of timber beetles are the so-called jewel beetles, the family Buprestidae. Within the park a good collector might find twenty species. The best known is the golden-lined Buprestid (Buprestis aurulenta Linn. Plate xvii, 6), a beautiful greenish or bronze-green beetle margined with gold. This species, which is about one inch in length, breeds in both pines and firs. Another species is Buprestis fasciata Fab., the male of which is green blotched with yellow and the female entirely green. These generally rest on green willow or poplar leaves, but during their young lives live in the Douglas fir. Two of the smaller members of this family sometimes do considerable damage through the work of their larvae. The first of these (Melanophila drummondi Kirdy) is a flat bronze beetle generally spotted with yellow which normally breeds in the dead Douglas and true firs. The other (Melanophila gentilis Lec.) is a rich blue-green or greenish-blue species which is restricted to the pines. Most of the members of. this family confine themselves to their food trees, but a few frequent flowers.

A third group of timber beetles are the so-called bark borers or engraver beetles of the family Scolytidae. The members of this family are generally small and of somber color, but they are at times very abundant and often tremendously destructive. The females bore tunnels beneath the bark where they deposit their eggs. The young, upon hatching, also bore tunnels, but generally in the opposite direction. As a result of the work of adult and larvae the tree is soon girdled. Though these beetles normally attack only the dead and dying trees, they at times turn their attention to the living ones. As a result there is an enormous loss of some of our very best timber every year. In the park itself one may notice many trees which are gradually dying as indicated by the yellowing of their tops, or trees with brown needles which are already dead. If one strips off the bark of any of these trees he will find the insects at work or if they have emerged he will find the results of their labors, the peculiar adult and larval tunnels which generally engrave both bark and sapwood.

Among the host of other beetles which are to be found on the herbage, on the ground, or in the water, but a few can here be mentioned. One of these is the true milkweed beetle (Chrysochus cobaltinus Lec. Plate xvii, 20), a chunky beetle of brilliant metallic blue color. It feeds upon the roots of the milkweed during the larval stage and on the foliage as an adult. In spite of its conspicuousness it is rarely molested by birds, no doubt because like the lady beetles it is very distasteful to them. Another interesting night-flying beetle is the large white striped June beetle (Polyphylla decemlineata Say. Plate xvii, 19), which is perhaps the largest of its family in the mountains. It often comes tumbling about one’s house or camp fire. A smaller and somewhat distant relative of the latter is the little "tumble bug" (Canthon simplex var. militaris Horn). This bluish-black beetle with red shoulders is a close relative of the sacred scarabeus of Egypt and has similar habits. If one watches the less frequented roads and trails he may be rewarded by finding some of these beetles at work hauling and pulling their precious pellets to a safe retreat. In the flower of the azalia another species of scarabid may be found. This is a very pretty pollen- and petal-feeding species (Hoplia dispar Lee.) which may appear in a dress of various colors-orange, brown, or green.

Among the ground beetles most species are of somber appearance, but there are a few exceptions. Two of these are the brilliant green tiger beetles (Cicindela perveridis Schaupp. Plate xvii, 1, and Cicindela depressula Casey). These are generally to be found only at the higher altitudes and generally on the grassy slopes just below the snow fields. Here their larvae sink their shafts into the earth and lie in wait for their prey while the active and long-legged adults seek theirs in the open chase.

In the water there are also many beetles both great and small. Some, like the water scavengers (Hydrophilidae), prefer warm and stagnant waters; others, like the whirligigs (Gyrinidae), most enjoy skating over the surface of the water; and still others, like the predaceous diving beetles (Dytiscidae), will live and thrive in even the coldest streams and lakes. The most interesting aquatic beetle in the mountains is Ampizoa insolens Lee. (Plate xvii, 3). It is a flattened beetle a little less than a half inch in length and in color an opaque black. It may be found crawling over the rocks and in the cold mountain streams. Although it lives in the water it looks more like a land dweller and is, in fact, equally related to both land and water beetles. It may be well to state that not one beetle in our country is poisonous, and that all may be handled with perfect safety. A very interesting beetle collection may easily be made by carrying a small vial of alcohol. Specimens should be removed and mounted on pins at the end of each day’s collecting.

There are in the park a goodly number of species of wasps, bees, ants, and other insects of the great order Hymenoptera. Most of these are small, but a few such as the horn tails or wood wasps are of fair size. The females of these insects are provided each with along, stout drill which enables them to bore straight into solid wood where they deposit their eggs. One of these, a large black species with orange wings (Urocerus Californicus Nort. Plate xvii, 2), has an appearance not unlike some of the large so-called tarantula hawks of the Southwest. It is harmless, however, for it cannot sting. The larvae often do considerable damage to timber and would do even more were it not for the fact that they are heavily parasitized by a large wasp of the family Ichneumonidae. One of these is a black and yellow insect (Megarissa nortoni Cress. Plate xvii, 5) which has a threadlike ovipositor longer than its body—so long, in fact, that it cannot be used in the usual way but must be curled over the back and brought down in front of the head before it can be used. With this wonderful instrument a hole is soon sunk in the timber where the wood wasp larvae are boring, and an egg is laid in their neighborhood.

Among the larger bees the carpenter bees of the genus Xylocopa are perhaps as notable as any. These black or bluish-black bees are fully as large as bumble bees and every bit as energetic. They have a habit of selecting well-seasoned wood such as an old cedar fence post or a portion of a building, and of excavating out a long chamber for their young much in the same way that a woodpecker does. If one approaches their home they circle about in a threatening manner but rarely do they attack one.

Other wood workers of this order which might be ment ioned are the large timber ants of the genus Camponotus. These are either black or red and black, and are the largest ants we have. Their nests are made in old logs and stumps and even in the hearts of growing trees when they have the opportunity to enter through an old scar. At times they do some damage but on the whole they are beneficial, for the workers destroy great numbers of destructive forest beetles; furthermore their wood work is, as a rule, only in old logs which are useless and should be removed. The winged adults of these ants often congregate in great numbers, like the lady beetles, about the summits of the lesser peaks.

Of the two-winged flies or Diptera there are also a great number, some of recognizable size and of peculiar interest. About the meadows and in the neighborhood of watercourses mosquitoes are often quite abundant. At higher altitudes, however, there is nothing to fear from these insects other than the annoyance of a few bites, for there are no malaria carriers or Anopheles much above five thousand feet. A small vial of oil of citronella will generally provide the means of repelling the meadow species. Horse flies and deer flies (Tabanidae) are also annoying at times, but the selection of proper camp sites away from marshy places, their normal breeding grounds, will generally give ample protection. Among the flies that will catch one’s eye during his rambles are the sun and hover flies (Syrphidae. Plate xvii, 12 and 14), many members of which, in their early stages, prey upon plant lice and which, in the adult stage, often mimic bees and wasps with which they often associate. One will also see many bee flies (Bombylidae. Plate xvii, 9 and 11), some hovering about the flowers like humming birds and others skimming over the ground to alight here and there in sunny spots. Often the robber flies (Asilidae. Plate xvii, 16) may be noticed. These hawks of the fly world are parasitic in their larval state and predaceous in the adult stage. The more gayly colored species haunt the forests where they may be seen sunning themselves on old logs, but the more somber colored, the grays and browns, frequent sandy areas.

Among the other orders of insects the grasshoppers will, of course, claim a certain degree of attention. Of these we have a few meadow species which, like the devastating grasshopper (Melanoplus devastator Scudd.), may at times destroy much of the upland feed but are generally not numerous enough to greatly exceed their demand as fish bait. Many species, however, are quite interesting to those who will take time to observe them. Some of these have beautiful under-wings of yellow, orange, red, blue, or black and some clap their wings together in flight and hover hawk-like as they rise, giving out such a strident sound that they can be heard for some distance. One of the latter, a blue-winged species (Cireottix thallassinus Saus.), is more common farther north, but a second, a black-winged species (Cireottix maculatus Scudd.), is fairly abundant at high altitudes in the middle Sierra. Many of the grasshoppers also show marked degrees of color protection, an example being the white and black species which chooses only granite slopes for a resting place.

Nests of termites or white ants may often be found in the woods beneath the bark of old fallen trees. We have but few species of these insects outside of the tropics, but one of our species is exceedingly large. This is a brown species (Termopsis nevadensis Hagen. Plate xvii, 13) which is found widely distributed throughout California but which is especially abundant in the mountains. The insects are very industrious creatures and will in a short time completely honeycomb a large log. Upon opening one of these nests one finds not only a host of their light colored workers and big-headed soldiers but also many winged adults. Many hours might be spent interestingly and profitably investigating the habits of these remarkable social insects. Even the bears are fond of the termites and the Indians likewise dig out their nests and use the eggs and larvae for food.

In the water one may find the interesting caddice fly larvae,

Some beetles, wasps, and flies of Yosemite National Park
Some Beetles, Wasps, and Flies of Yosemite
National Park
each enclosed in its own peculiar case, and also the flat bodied larvae of the rock flies crouching close against the rocks. The adults of both insects will be found in the immediate neighborhood, the moth-like caddice flies dancing over the waters and the rock flies resting along the banks. A somewhat distant relative of the above flies is the night-flying brown lace-winged fly (Polystoechotes punctulatus Fab. Plate xvii, 10). It is the largest of its race and peculiar in that its larvae have never been discovered.

In this short article it is possible to mention briefly only a few representative species of the different types of insects found in Yosemite National Park. The following list of references will aid those who wish to investigate more thoroughly the fascinating science of Entomology.


Comstock, J. H. and A. B., 1895. A Manual for the Study of Insects. (Comstock Publishing Co., Ithaca, N. Y.) pp. 701, cuts 799.
How to Know the Butterflies. (Comstock Publishing Co., Ithaca, N. Y.) pp. 311, 45 col. pls.

Essig, E. O., 1915. Injurious and Beneficial Insects of California. (Calif. State Com. of Hort.) pp. 541, illus. 503.

Holland, W. J., 1899. The Butterfly Book. (Doubleday & McClure Co., N. Y.) pp. 382, col. pls. 48, figs. 183.
1908. The Moth Book. (Doubleday, Page & Co., N. Y.) pp. 479, pls. colored 48, figs. 263.

Howard, L. O., 1912. The Insect Book. (Doubleday, Page & Co., N. Y.) pp. 429, pls. 48, illus. 264.

Kellogg, Vernon L., 1905. American Insects. (Henry Holt & Co., N. Y.) pp. 674, pls. 13, figs. 812.

Lutz, F. E., 1918. Field Book of Insects. (G. P. Putnam’s Sons, N. Y.) pp. 509, pls. 101.

Scudder, S. H., 1881. Butterflies. (Henry Holt & Co., N. Y.) pp. 322, illus. 201.

Wheeler, W. M., 1910. Ants. (Columbia Univ. Press, N. Y.) pp. 663, illus. 286.

Woodworth, C. W., 1913. Guide to California Insects. (The Law Press, Berkeley, Cal.) pp. 360, figs. 361.

Wright, W. G., 1905. The Butterflies of the West Coast. (Whitaker, Ray & Co., S.F.) pp. 257+vii, col. pls. 32.

Next: Trees of YosemiteContentsPrevious: Fishes of Yosemite

Home A - Z FAQ Art Prints Online Library Discussion Forum Muir Weather Maps About Search
Online Library: Title Author California Geology History Indians Muir Mountaineering Nature Management