August 1945

Vol. XXIV August, 1945 No. 8

THE MONTHLY PUBLICATION OF THE YOSEMITE NATURALIST DEPARTMENT AND THE YOSEMITE NATURAL HISTORY ASSOCIATION

F. A. Kittredge, Superintendent C. F. Brockman, Park Naturalist M. V. Walker, Associate Park Naturalist

VOL. XXIV AUGUST, 1945 NO.8 OYSTER SHELL SCALE IN YOSEMITE NATIONAL PARK

By Myrl V. Walker, Associate Park Naturalist When the oyster shell scale was and old plants are killed. Infestations ocfirst discovered in Yosemite Valley cur in all parts of the Valley from El Portal is not definitely known, however, atto Mirror Lake. Probably the most damage tention was called to its presence has been done at the mouth of Cascade and destructive capabilities almost Creek, in Sentinel Meadows and west of twenty years ago in a report preYosemite Creek near its mouth. pared by members of the Forest In- "In one grove in Sentinel Meadows west sect Laboratory, Stanford University, of the giant yellow pine, 23 large cottonCalifornia. This report was based on woods are dead and eight are barely observations made during the sumalive. At the mouth of Cascade Creek 52 mer of 1928. In this survey the followcottonwoods are dead and 121 infested and ing statement was made regarding practically dying. In the meadow across the importance of the oyster shell from the post office numerous young trees scale : are infected. Large trees do not die sud- "The oyster shell scale is a serious denly but slowly, a few branches year enemy of fruit, ornamental and forest trees after year. Some small trees die a few and shrubs throughout most of the United years after they become infested." States. It has been reported as killing enThe oyster shell scale has been tire stands of ash and other trees in some described as a "living pumping localities. There is a heavy infestation in machine, which rests quietly on the some parts of the Yosemite, and all evibark and with its long beak inserted dence indicates that unless the pest is into the sap conducting organs bebrought under natural or artificial control, neath the bark, and pumps or sucks it will kill most of the cottonwood, willow, out the sap. Each scale does not get and red dogwood on the floor of the Vala great deal of sap, but when there ley within the next ten years. Already are millions of them working side by numerous cottonwood, willow and red dogside the drain on the plant is too wood are dead, and many more are heavigreat, and the vital, soft growing ly infested and slowly dying. Both young layers are injured so that they die."

It is rather difficult to describe the oyster shell scale so that it may be recognized by the average observer, but it is believed that the accompanying illustration is sufficiently clear to enable one to identify this scale. One writer gives the following brief description, "The oyster shell scale is readily distinguished from all other scale insects—by its peculiar shape and color, resembling a miniature elongate, curved oyster shell of a dark brownish bark-like color. The convex scale covering the body of the female is about 1/8 of an inch long and consists of two minute cast skins at the smaller end and a large scaly portion gradually secreted from the body of the insect un derneath. The male scale is much smaller and rarely seen on fruit trees; they are often abundant on ash. Old lifeless scales often adhere to the bark for several years." After discussing how this scale may be recognized on the trees, and how the scale injures the tree, the members of the Forest Insect Laboratory Investigating Committee made the following summary or conclusion: "The investigations carried on during the summer of 1928 indicate that at present there are two important insect control problems in the forests on the floor of Yosemite Valley.. The second problem is that of protecting the cottonwood, willows and red dogwoods from the ravages of the oyster shell scale which has come into the Valley and is very actively attacking and destroying many fine specimens of these native species of attractive shrubs and trees. Judging from what the scale has done in the past five years, we have every reason to believe that most of the cottonwoods will be killed in the next ten years unless adequate control measures are developed. " As a result of this investigation and in accordance with the recommendations, attempts were made to control the ravages of the oyster shell scale. It is evident, however, that control measures were not very effective in controlling the spread nor in reducing the destructiveness of this scale insect. Another report which gives us

Further information on the oyster shell scale in Yosemite Valley is an article on scale insects by E. O. Essig of the University of California, October 1928. Mr. Essig makes the following statement: "The oyster shell scale, (Lepidosaphes ulmi Linn.), is exceedingly abundant on the willows and young poplar or cottonwood trees on the floor of the valley. In fact it often completely encrusts the branches of entire clumps of willows, many of which have been killed by the coccid. This scale was probably introduced into the valley on apple trees following the settlement of J. C. Lamon there in 1859 and J. M. Hutchings in 1864. Both of these residents planted quite extensive orchards which are still in existence. While the scale may still be found on the apple trees of their orchards, it is by no means as abundant and destructive to the fruit tree as it now is to the native willows and cottonwoods." A large number of references may be found descriptive of the oyster shell scale and its introduction, probably from East Asia, for it is not a scale insect native to North America. Like the San Jose scale it was introduced into the San Joaquin valley by early plantings of trees or shrubs brought over from East Asia. It is interesting to note that even though the oyster shell scale was probably brought in on apple trees introduced into Yosemite Valley, the scale has since attacked other trees that now appear to serve as a better host plant than the original one. In a "History of Entomology" Essig calls attention to the fact that the oyster shell scale was attacking other trees besides the apple in Yosemite Valley, and he makes the following statement: "This scale insect was introduced into the Yosemite Valley on apple trees at an early date and has thrived unusually well. It has also attacked the native poplars and willows severely, and during the summer of 1928 I noted most of the willows growing on the Valley floor completely encrusted and many clumps entirely killed by the insect." Further reference to the oyster shell scale in Yosemite National Park may be found in the report by the Yosemite School of Field Natural History for the summer of 1939, when they reported on the presence of this scale in the Swamp Lake area north of the Tuolumne river. In 1938 Mr. Joseph Dixon had noted aspens in this area being attacked by the oyster shell scale, but he stated that only a few of the trees were losing their leaves and that the scale, although

present, was not abundant. Within the area. Of these one was prostrate and the year it is apparent that the scale retained foliage at its tip. A second had had made rapid progress, for many life only in the central portion. The tip of the trees examined in 1939 were was standing, but with the exception heavily infested and were being the uppermost extremities it was nearly killed quite rapidly. dead." In the report of the Yosemite The presence of oyster shell scale School of Field Natural History for on trees and shrubs in the wildflower 1940 the following report was made garden back of the Yosemite Museum on the oyster shell scale infestation has been noted for several at Swamp Lake Meadow : years, and an attempt has been "The progress of the scale during the made to control it in the garden. A past year seems to have been very rapid recent survey of the trees and shrubs around the southern margin of the lake. around the Museum and in the wild At the present time only 20 trees out of apflower garden reveals that the oyster proximately 50 over ten feet in height are shell scale is present on a variety still alive, and these show life only in the plants and that it is making progress uppermost branches. The largest group in spite of the present methods of of living trees, 35, is found at the north.control. Some of the shrubs with par

east end of the lake. This grove, which is ticularly bad infestations at theabout 15 by 60 feet, contains a few dead present time are the redbud just out trees, but the scale has caused the loss side the Museum door on either side of all the leaves except at the tips of the of the walk. The scale may be ob upper branches." served on several branches, and In the report of the Yosemite School there are a number of the main of Field Natural History for 1941 adstalks or stems with a diameter of ditional observations were made on one and one-half to two inches that the oyster shell scale in the Swamp are literally covered with the scale. Lake area as follows : It is apparent that these branches "A careful study of the relationship bewill surely be killed in a short time. tween the oyster shell scale and the quakIn the many reports of host plants ing aspen was made to determine the ecofor the oyster shell scale there are logical changes which have occurred since long lists of trees and shrubs, but in the 1940 study of this problem. in the no instance have I been able to find northeast part of the meadow the upper where the redbud has been listed as one-third of 15 mature trees still retained subject to attack by the scale. If the some foliage and the bark is intact but shrubs by the Museum are any indicracked and entirely covered with scale. cation of the present trend of this Three mature trees which still contained scale in attacking redbuds, there is life were noted in the southeast corner of reason to believe that all redbuds

will soon be destroyed within the On the other hand, it is now apparevery near future. ent that little could be gained today In the wildflower garden this scale by the elimination of the apple oris present on the ceanothus, quaking chards, for the apple trees no longer aspen, cottonwood, and willow, but serve as a major host plant for the past efforts to control it in the garden oyster shell scale. have thus far been successful in preMany observers have been interventing its spread to the alders, ested lately in the changing condiwhich in other areas have been corntions in Yosemite Valley, particularly pletely destroyed. Some very bad in regard to the change in meadow infestations occur on quaking aspen growth, open vistas, and encroachand willow, and one young willow ment of cone-bearing trees upon the tree with a diameter of nearly three former open vistas and so called inches has been killed by the scale. meadows. It is evident that the attacks of the oyster shell scale on When the early settlers in Yosemite Valley planted small apple orchards, they little realized the great willows, red dogwood, cottonwoods, changes that would be brought about alders, and ceanothus that once in the Valley simply because of the formed the borders of the meadows introduction of the apple trees. The has been to a certain extent responsible for this change. Although it is introduction occupied by these small or-well known that shrubs were occachards did not interfere to any ex-sionally "cleared" from the meacupied by the native trees and dows, such clearing was probably shrubs, however, the introduction of of minor consequence in the destructhese trees which were, quite untion of the dense, brushy areas along known to the early settlers, hosts to the streams or the brushy areas bora very prolific scale insect, did bring dering the meadows along the marabout an unpredictable alteration in gins of the forests of oak and pine. the condition of the native flora. These dense patches of shrubbery Had those early settlers known of no doubt once served as a barrier or the destructive capabilities of the buffer zone to the encroachment of scale insect which they inadvertenthe oaks and conifers, but their desly introduced, they would no doubt truction, accounted for at least in part have gladly sacrificed the pleasure by the oyster shell scale, has opened of a few eating apples in order to prethe way for the oaks and pines to serve the native trees and shrubs get a start in the "open vistas" that which were so much a part of the were once present in Yosemite Valoriginal beauty of Yosemite Valley. ley.

THE ARTIST'S YOSEMITE --- AN APPRECIATION

By Marion William Batchelor My visits to the Yosemite have shows technical knowledge and been in the late summer and early influence of careful training. autumn. I have not yet seen the sun shows also the effect of a new subinscribe its yearly log from solstice ject, wild and untamed. to solstice. Yet a visit under favor- But I never fully understood the able auspices may leave a unity of picture until one September night I impression which falls into a natural the moon little short of the full, enperspective and which might be lost tered a meadow, its late summer darkby a longer sojourn. ness easily supporting a quiet, free Within the stone, vine-draped por- to feel a new, chill layer of air, pertals of the Museum, I like to study a and perfumed by ritual since suncertain canvas by Bierstadt. Therein down. All the landscape was simpli- I see a drama unfolding—a stretch of fied in the vague light; the great water; a night fire in the distance; south walls sculptured into awesome huge rock formations rising like stu- aspect by successive lunar beams. pendous bastions, rising toward por- the moon itself just skirting the rock tent clouds, through which breaks rims. From the depths of wooded the moon, full and foreboding. The shadow, remote and baffling, came picture, painted many decades ago, the notes of an owl. Then Bierstadt

Spoke — for comprehension had cient and healthy in the face of na-come. I understood what he saw and ture, purify the mind alike from dull-it. I paid homage to one who, when ness and hysteria." travel to reach this place was itself "The fact of its great age and spe-an arduous task, laden with equip- cial beauty further recommends this ment, wandering day after day in country to the artist. The field was this fantastic land, by night sought chosen by men in whose blood there shelter and fire near giant lichened still raced some of the gleeful and rocks or some aged, incense-laden solemn exultation of great art... tree. So it was, too, with men like "In this continual variety the mind Keith and Moran. Their spirit peris kept vividly alive. It is a changeful vades the place. They knew its aweplace to paint, a stirring place to live some peaks, fanned by the winds; in. As far as your foot carries you, its valleys, warmed by a merciful you pass from scene to scene, each sun; color now strained to its highest endeared with sylvian charm, each key, now scattered in atmospheric vigorously painted in the colors of vagueness. the sun. The air, which is cooled all The lines in Stevenson's essay on day in crypts of underwood, the in-Fontainebleau could have been writ- fluence of the resin, the listening si-ten for the Yosemite, as the deepest lence of the groves, the unbroken sol-meaning of forests and mountains is itude, the sunlit distance, the scurry-much the same everywhere: "It is a place that people love more owy flitting of deer, and that heredi-than they admire. The vigorous for- tary spell of forests on the mind of est air, the silence,... the wildness man who still remembers and sa-of tumbled boulders, the great lutes the ancient refuge of his race— age and dignity of certain groves— legend and sight, sound and silence these are but ingredients, they are alike gratify and stimulate the heart." not the secret of the philtre. The It is for you, artists, to comprehend place is narrative; the air, the light, this poetry of life and earth. If you the perfumes, and the shape of do not, then discard your colors and things, concord in happy harmony. brushes; they will be of no use. The artist may be idle and not fear To you who are not artists, enjoy the "blues." He may dally with his this great al fresco school where we life. Mirth, lyric mirth, and a vivacan learn all our lives. When you cious, classical contentment, are of are surfeited with the valley, slip the very essence of the better kind of your packs over your shoulders and art; and there,... he has a chance take to the trails. Nature, with her in-to learn or to remember. A larger exhaustible secrets, will reward your air, a higher heaven, something aneffort.

AN INTERESTING BUTTERFLY MIGRATION

By C. Frank Brockman, Park Naturalist About June 10, for a period of approximately three days, Yosemite visitors were treated to a spectacular migration of California tortoise-shell Photo courtesy of E. O. Essig butterflies (Nymphalis californica). As noted in "Butterflies of California" by J. A. Comstock (pp. 127-130) this swarm of California tortoiseshell butterflies was not, in a true sense, a migration. This species is one of several that may over-winter as adults or as chrysalids. Since caterpillars and chrysalids are often heavily parasitized, the abnormal increase in numbers of this insect which occurs periodically is probably the result of a reduction, for some reason, of the parasites that usually hold them in check. When, the preferred food plant, in this case various species of Ceanothus, has been largely stripped from a given area, the adults in emerging from the chrysalis are forced to fly to other areas where a sufficient food supply is found before laying their eggs. Often the caterpillars are so abundant that they strip the foliage from the Ceanothus over wide areas, and it is interesting to note that such was the case in the Mariposa region below the park boundary previous to this migration. This butterfly is one of the most common in the western mountains being distributed from the Rockies to the Pacific Coast. According to Professor E. O. Essig of the University of California swarms such as observed here last June are not uncommon. Regions in California which are especially characterized by such large scale, periodic dispersal or migratory swarms are those in the vicinity of Mt. Shasta, Mt. Lassen, Lake Tahoe and Donner Pass, American River, and Yosemite. Professor Essig also states that this species is occasionally abundant in the Coast Range of middle California.

Digitized by Yosemite Online Library Dan Anderson