UNIVERSITY OF CALIFORNIA PUBLICATIONS COLLEGE OF AGRICULTURE BITY OF CAUFurWUfc BRANCH OF THE COLLEGE Of A6«:CULTDRf COPY 2 AGRICULTURAL EXPERIMENT STATION THE PURPLE SCALE By H. J. QUAYLE BULLETIN No. 226 (Berkeley, Cal.) Fri 1'^ SACRAMENTO IC$U.RD,SON j'- - - SUPERINTE£ I 1912 . f Benjamin Ide Wheeler, President of the University. EXPERIMENT STATION STAFF. E. J. Wickson, M.A., Director and Horticulturist. E. W. Hilgard, Ph.D., LL.D., Chemist (Emeritus). W. A. Setchell, Ph.D., Botanist Leroy Anderson, Ph.D., Dairy Industry and Superintendent University Farm Schools. M. E. Jaffa, M.S., Nutrition Expert. R. H. Loughridge, Ph.D., Soil Chemist and Physicist (Emeritus). C. W. Woodworth, M.S., Entomologist. Ralph E. Smith, B.S., Plant Pathologist and Superintendent of Southern California Pathological Laboratory and Experiment Station. G. W. Shaw, M.A., Ph.D., Experiment Agronomist and Agricultural Technologist, in charge of Cereal Stations. E. W. Major, B.Agr., Animal Industry. B. A. Etcheverry, B.S., Irrigation Expert. F. T. Bioletti, B.S., Viticulturist. W. T. Clarke, B.S., Assistant Horticulturist and Superintendent of University Exten- sion in Agriculture. John S. Burd, B.S., Chemist, in charge of Fertilizer Control. J. E. Coit, Ph.D., Assistant Pomologist, Plant Disease Laboratory, Whittier. George E. Colby, M.S., Chemist (Fruits, Waters, and Insecticides), in charge of Chemical Laboratory. H. J. Quayle, M.S., Assistant Entomologist, Plant Disease Laboratory, Whittier. H. M. Hall, Ph.D., Assistant Botanist. C. M. Haring, D.V.M., Assistant Veterinarian and Bacteriologist. E. B. Babcock, B.S., Assistant Agricultural Education. W. B. Herms. M.A., Assistant Entomologist. J. H. Norton, M.S., Assistant Chemist, in charge of Citrus Experiment Station, River- side. W. T. Horne, B.S., Assistant Plant Pathologist. C. B. Lipman, Ph.D., Soil Chemist and Bacteriologist. R. E. Mansell, Assistant Horticulturist, in charge of Central Station grounds. A. J. Gaumnitz, Assistant Agronomist, University Farm, Davis. N. D. Ingham, B.S., Assistant in Sylviculture, Santa Monica. T. F. Hunt, B.S., Assistant Plant Pathologist. P. L. McCreary, B.S., Chemist in Fertilizer Control. E. H. Hagemann, Assistant in Dairying, Davis. R. M. Roberts, Farm Manager, University Farm, Davis. B. S. Brown, B.S.A., Assistant Horticulturist, University Farm, Davis. J. I. Thompson, B.S., Assistant Animal Industry, Davis. J. C. Bridwell, B.S., Assistant Entomologist. L. Bonnet, Assistant Viticulturist. F. C. H. Flossfeder, Assistant in Viticulture, University Farm, Davis. P. L. Hibbard, B.S., Assistant Fertilizer Control Laboratory. F. E. Johnson, B.L., M.S., Assistant Soil Chemist. C. H. McCharles, M.S., Assistant Agricultural Chemical Laboratory. B. A. Madson, B.S.A., Assistant Experimental Agronomist. Howard Phillips, B.S., Assistant Animal Industry, Davis. Walter E. Packard, M.S., Field Assistant Imperial Valley Investigation, El Centro. L. M. Davis, B.S., Assistant in Dairy Husbandry, University Farm, Davis. S. S. Rogers, B.S., Assistant Plant Pathologist, Plant Disease Laboratory, Whittier. H. A. Ruehe, B.S.A., Assistant in Dairy Husbandry, University Farm, Davis. C. O. Smith, M.S., Assistant Plant Pathologist, Plant Disease Laboratory, Whittier. E. H. Smith, M.S., Assistant Plant Pathologist. C. L. Roadhouse, D.V.M., Assistant in Veterinary Science. F. M. Hayes, D.V.M., Assistant Veterinarian. M. E. Stover, B.S., Assistant in Agricultural Chemical Laboratory. W. H. Volck, Field Assistant in Entomology, Watsonville. E. L. Morris, Field Assistant in Entomology, San Jose. E. E. Thomas, B.S., Assistant Chemist, Plant Disease Laboratory, Whittier. A. B. Shaw, B.S., Assistant in Entomology. G. P. Gray, M.S., Chemist in Insecticides. H. D. Young, B.S., Assistant in Agricultural Chemistry, Plant Disease Laboratory, Whittier. A. R. Tyler, B.S., Assistant in Plant Pathology, Plant Disease Laboratory. Whittier. E. W. Rust, A.B., Assistant in Entomology, Plant Disease Laboratory, Whittier. L. T. Sharp, B.S., Assistant in Soils. W. W. Cruess, B.S., Assistant in Zymology. J. F. Mitchell, D.V.M., Assistant in Veterinary Laboratory. W. B. Boys, Assistant Cerealist. Anna M. T^ute, Scientific Assistant, United States Department of Agriculture. J. C. Roper, Patron, University Forestry Station, Chico. E. C. Miller/ Foreman, Forestry Station, Chico. D. L. Bunnell^ Secretary to Director. CONTENTS. Page. EARLY HISTORY 319 INTRODUCTION INTO CALIFORNIA 319 DISTRIBUTION _ 321 Over World 321 In California 321 ECONOMIC IMPORTANCE 323 FOOD PLANTS 325 DESCRIPTION OF THE STAGES 32G The Egg 326 The Active Larva 326 The Second Stage Male 326 The Propupa 328 The Pupa 328 The Adult Male 328 The Adult Female 328 LIFE HISTORY AND HABITS 330 The Egg 330 The Active Larva 330 Locomotion 330 Settling 332 Formation of the Scale 333 The Process of Molting , 334 Development 335 Seasonal History 336 PARASITE 337 Aspidiotiphagus citrinus Craw 337 PREDACEOUS ENEMIES 33S RELATED SPECIES 338 BIBLIOGRAPHY 330 Digitized by the Internet Archive in 2012 with funding from University of California, Davis Libraries http://www.archive.org/details/purplescale226quay THE PURPLE SCALE. Lepidosaphes beckii Newm. By H. J. Quayle. EARLY HISTORY. The purple scale, Lepidosaphes beckii, was first made known by New- man in an account appearing in the English publication "The Ento- mologist" in Februrary, 1869. 1 In August of the same year Packard2 in this country gave a brief description of the same insect, calling it Aspidiotus citricola. Newman had given it the genus name Coccus, which has since been changed, while his species' name beckii still stands. From 1870 to 1876 a few articles appeared on this insect in France and Italy. Glover has the second notice of its occurrence in the United States in the United States Department of Agriculture Year Book for 1876. He stated that it was found on imported lemons in Jackson- ville, Florida, in 1857. The description of this insect given by Packard was made simply from unpublished figures and, of course, was inadequate. The first complete description was given by Comstock in his 1880 report, but he adopted the same specific name as that given by Packard. Introduction into California. — The purple scale seems to have been introduced into California directly from Florida in 1888 or 1889. In the report of the California State Board of Horticulture for 1893 Alexander Craw states that "four years ago two carloads of orange trees were received in this State from Florida and planted in Los Angeles and San Diego counties without disinfection. The result is that the climate that has been preached us by importers of Florida stock as unfavorable to the development of this species of scale has proved to be the opposite, for on a visit to the above counties last summer I was shown trees completely covered with purple scale. ' ' The May number of the Rural Calif ornian for 1889 was largely occupied with discussions of the prob- able damage which would result from the importation of Florida scales, among which the purple was the most important. Dr. Riley, writing in Insect Life in 1889, states that "we have received a number of letters from California asking our opinion on the necessity for quaran- tine, and have replied that while there seems reason to believe, and we are inclined to believe, from the evidence at hand, that the scales men- JThe Entom. IV, p. 217 (1869). 2Guide to the Study of Insects, p. 527 (1869). 320 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. Bulletin 226] THE PURPLE SCALE. 321 tioned will not flourish in certain parts of southern California, like Riverside, where the heat and dryness are great, yet it will be unwise to depend too much on the limited experience of the past. We have, therefore, reiterated our convictions as to the necessity of using every precaution to prevent their introduction." Fig. -Map showing distribution of the purple scale over the southern California citrus belt. DISTRIBUTION. Over World. — The purple scale is widely distributed over the world, as reference to the map will indicate. The localities as represented by the +s on the map are as follows : Europe, Maderia, West Africa, Mauritius, Ceylon, Japan, Australia, Tasmania, New Zealand, Fiji, Hawaiian Islands, Bermuda, Java, West Indies, Paraguay, Florida, Louisiana, Colorado, and California. The Paraguay locality given above is based upon material received in July. 1911. Mr. C. F. Mead collected some orange leaves that had a sickly appearance from Pirapo, Paraguay, and sent them to Professor Coit of this station. The leaves proved to be infested with typical purple scale. Hitherto there have been no published records, to our knowledge, of this scale occurring in that locality or even on the continent of South America. In California. — At the present time the purple scale occurs in the following counties in California : San Diego, Los Angeles, Orange, 322 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. Ventura, and Santa Barbara. It does not occur, thus far at least, in the citrus sections of the San Joaquin and Sacramento valleys. Neither does it occur in Riverside or San Bernardino counties. From its distri- bution in the above coast counties it would appear that it thrives best in a cooler and moister climate, and in this respect it is similar to the iT"^' *$M y<- ■*■ > • JP*" jtiG**** ■ <*' >:-: W vf « n, W/ Wk vim I! Fig. 9. — Pygidium of adult female purple scale. xl60. The adult female will average 1.2 mm. in length and .7 mm. in width. On the lateral margin, beginning at the anterior end, are from three to four broadly rounded extensions, and following these from three to four pointed protuberances, all excepting the most anterior having short, blunt spines at tip. There are always three pairs of lobes visible and often a fourth. The median lobes are broad and bluntly pointed, with more or less indication of serrations. The second pair is broad and deeply notched, the third short and broad with serrated edge. Fig. 10. — Purple scale. 1. Development of scale covering. xl3. 2. The beginning of the formation of the scale covering. xl20. 3. Male and female scales, showing comparative size and shape. x27. 4. Dorsal and ventral view. 5. Two stages of larva of Aspidiotiphagus citrinus within purple scale. 6. Pupa? of same within scales. 7. Exit holes of A. citrinus. 8. Formation of covering after first molt. Bulletin 22G] THE PURPLE SCALE. 329 Fig. 10. — See opposite page for legend. 330 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. There are two spine-like plates between the median pair between the first and second, and second and third. There are also two between the third and what might be called the fourth pair, which show dis- tinctly in some of the specimens. Another pair of these spine-like plates is found at the extreme edge of the segment. The spines that are conspicuous are two on each of the median lobes and one at the incision of the second. LIFE HISTORY AND HABITS. The Egg. — The eggs of the purple scale are protected, not only on the upper side of the scale covering, but on the under side, by a lighter and more cottony secretion, so that thej^ are practically surrounded on all sides excepting at the posterior end. They are arranged in regular rows and standing partly on end. The number will vary from forty to eighty. These are deposited over a period of three or four weeks. The time of hatching will vary from fifteen days in summer to three weeks or longer in the winter months. Those nearest the tip are the oldest and are the first to hatch. As the quota of eggs are deposited, the insect diminishes in size and contracts toward the anterior end of the scale, filling the space thus left with eggs. THE ACTIVE LARVA. The active larva usually wanders about over the plant for a short time before settling. This period will vary from a few hours to two or three days, the majority becoming fixed within one day after emerging from the parent scale. The scales upon hatching may not make their way from beneath the scale immediately, expecially if the weather is cool. But not many, generally not more than two or three, will be found hatched and not yet emerged. Locomotion. — The rate at which the young larva will crawl over smooth paper varies considerably, according to the temperature. With a temperature of 64° F., the maximum distance traveled during a two- hour period was 27 \ inches, while a distance of 111 inches was covered when the temperature was 89°. Locomotion of Young Purple Scale. Number examined. Date. H\ Time. Tempera- ture. Distance. Average distance. 1 November 18. 1910 9:20-12:20 p. m. 64° 9 inches 1 November 18, 1910 •9:20-12:20 p. m. 64° 21 inches 1 November 18, 1910 9:20-12:20 p. ra. 64° 27.50 inches 19 inches 9 November 2, November 2 , 1910 9:30-11:30 p. m. 9:30-11:30 p. m. 68° 68° 28 inches 37.75 inches 2 1910 33 inches 3 July 21 , 1910 1:20- 3:20 p. m. 89° 111 inches 111 inches Bulletin 226] THE PURPLE SCALE. 331 Fig. 11. — Actual tracings of the movement of young purple scales for a two-hour period; reduced 7 times. Above, the temperature was 64° and the average distance covered was 19 inches. Below, the temperature was 89° and the distance covered was 111 inches. 2— bul226 332 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. The rate and distance of travel noted above was on smooth paper. The conditions were thus more favorable than will ever be likely to obtain in nature. Counting the maximum length of life as an active larva when deprived of food at four days, the highest possible record under the most favorable conditions would be a total of 444 feet. But obstacles to travel, such as a pulverized soil, make a very different story. With a temperature of 86° at 9 a. m., twenty-five active young were placed unharmed in the center of an area of sand, having a five-inch radius. None reached the edge during the same day or the day fol- lowing. Another similar experiment resulted negatively. A third, similar to the others, was started, and out of twenty-five scales liber- ated, one reached the margin in 5f hours. This was the only one that succeeded in crossing a five-inch strip of sand. The following records were made on a three-inch radius of sand : Number liberated. Temperature. Time. Results . 20 20 10 63°F 82° F 65° F 1:30 p. m. 9:45 a. m. 9:30 a. m. None reached margin 2 out at 12:30 2 out at 1 p. m. Other tests were made with orchard soil, but there seemed to be little difference over that of sand. It will thus be seen that the young purple scales are able to make but little progress over soil that is well cultivated. Only an exceedingly small percentage of those liberated crossed but three or five inches of such soil. If the soil is compacted as after heavy rains or in irrigation furrows considerable progress may be made, but even here the factor of their own powers of locomotion in their dis- tribution is very small. Settling. — Out of 240 scales liberated in leaf cages at different times from March to September, 122 or about 50 per cent became established. This should represent a fair average, or, if anything, an under estimate of the percentage, since the young were liberated on suitable leaves and protected from all outside agencies. There seems no doubt that condi- tions as they ordinarily obtain in nature would decrease the above percentage considerably. It may, therefore, be counted that at least 50 per cent of the scales fail to become established even under the most favorable conditions. The young purple scale may settle either on the branch, leaf, or fruit. The branches or leaves are the first to become infested, but if they are abundant on these, the fruit in the vicinity will become badly infested also. Where the numbers are not large there is a tendency for the young scales to settle along the midrib or large veins of the leaf. This tendency was usually strongly shown in our breeding cages. They do Bulletin 226] THE PURPLE SCALE. 333 not migrate far from the parent as a rule. It is most usual to find this scale limited to but a portion of the tree, and while this portion may be so severely infested as to be killed, the rest of the tree may be in a healthy condition and comparatively free from the scale. The infested portion is nearly always on the lower side of the tree and later extends upward covering the greater part of one side of the tree. This side is not necessarily away from the sun for it has been noted on the east, south and west sides of the trees. Formation of the Scale. — Upon settling, the young larva of the purple scale very soon secretes a couple of rather coarse cottony threads from the anterior end of its body, apparently from just under the margin of the anterior end. These are long entangling threads that extend entirely over and around the insect. The function of these is undoubt- edly a provision for protection while the more compact covering is being secreted. At any rate these entangling threads answer this pur- pose, for it has been many times observed that a young Coccinelid larva upon striking them will immediately back away or turn in another direc- tion without molesting the insect thus protected. These entangling threads remain until the insect is about half grown, and, where the young scales are numerous, they form a fuzzy coating over the infested surface. Some practical fumigators use this as a criterion that the insect is in the best stage for treatment; and this is correct, for such threads are lost as they approach maturity. After these two long protecting threads are formed the insect begins the secretion of the permanent scale. These threads are very much finer than the first ones and cover the insect more compactly. The cov- ering for a day or two is of course thin enough to make out very readily the insect beneath. This covering is started at the posterior end, and, after about one day, only the anterior one fourth of the insect is free. The long, entangling threads are still present and these remain for a considerable time. Later, however, after the scales are about one half grown they are lost. After the covering has reached the anterior end and the insect is completely covered, it still extends the covering in two horn-like projections as shown in Figs. 10-12. If these are care- fully lifted the antennae will be found beneath so that they serve as a protection to the antennae for a time. As the insect grows older, the scale becomes more compacted. When the first molt occurs, the entire skin is incorporated in the dorsal scale. The insect works its way out beneath, leaving the covering which has been secreted, and the cast skin, above it. Very soon, however, the scale is extended posteriorly so that the cast skin becomes an oval, dark brown plate at the anterior tip of the scale. The second cast skin, which is very much larger than the first, is also incorporated into the dorsal scale covering. The secretion is continued and the scale extended beyond the second exuvium until the 334 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. part beyond becomes the length of the rest of the covering. As the female becomes mature and egg laying begins, a considerable secretion is formed on the under side. This is secreted from the sides of the insect, the two films meeting down the central line. A narrow strip of this ventral scale is formed on either side of the scale beneath during the earlier stages, particularly at the anterior end, and this gradually widens and extends more posteriorly as the insect becomes mature. But no part of the cast skins are found in this ventral scale which is entirely the secretion of the insect. In the case of the male only the first cast skin is incorporated into the scale covering. This is exactly similar to that of the female, since there is no difference in the sexes until after the first molt. But all succeeding cast skins of the male are pushed back and from beneath the scale covering. The narrow, elongate covering, typical of the male insect, is formed entirely during the second stage of the insect. The Process of Molting. — In the case of the purple scale the molting process is very different from that of Chrysomphalus aurantii and also different from that of the unarmored scales as represented by Saissetia olece. In the case of the red scale, the rent in the old skin occurs along the margin of the body, so that the dorsal half becomes incorporated in the dorsal scale and the ventral half of the ventral scale. In Saissetia olece, Coccus hesperidum, and others of the unarmored group, the skin is split at the anterior end and pushed backward and entirely free from the insect. The rent in the skin of the purple scale occurs on the ventral side in a more or less irregular line a short distance from the margin. At the anterior end this is between the rostrum and the antennas, on the sides, between the legs and the body margin ; and at the posterior end, just anterior to the pygidium. The insect first emerges, presumably at the anterior end (the process can not actually be observed) and later pulls the posterior end forward and downward, leaving the old skin directly above it. From the appearance of the cast skin the insect could very readily, simply by a contraction of the body, free itself from the narrow projecting portion of the ventral scale at the anterior end. In the case of the posterior end, the rent does not occur so near the margin, hence the projecting scale is somewhat broader than that at the anterior end. But once the anterior end of the insect was free, it would be easy to liberate itself from this posterior pocket. That Fig. 12. — First cast skin of purple scale ; ventral view, showing how skin is split and ventral por- tion with legs and mouth parts pushed back. Bulletin 22G] the purple scale. 335 the anterior end is first freed from the old scale is further shown by the fact that the old ventral skin is pushed backward, which would not be possible in any other case. The exuvium, therefore, is entirely in the upper or dorsal part of the scale covering. After clearing in potash it will be seen that the antennas are intact at the anterior end, the rent having occurred posterior to them, so that their position has not been changed in the molting process. At the posterior end all the characters of the pygidium can be made out as clearly as in the perfect insect, for these, likewise, have not been disturbed. As in the opposite end the insect has simply pulled itself from within, leaving all the characters undisturbed. The ventral por- tion of the molted skin, instead of being simply laid down beneath the insect, is pushed posteriorly as far as the pygidium, or to the edge of the rent at the posterior end. Here the legs and rostrum may be made out, the whole being more or less doubled up from the process of pushing backward underneath the insect. Development. — The first molt of the purple scale occurs about twenty- six days after birth. Up to this period there is no difference between the sexes, but the difference becomes sharply marked immediately after this stage. In the case of the female, the period between the first and second molts is about the same as that from birth to the first molt. The second molt brings the female to maturity, at least so far as the molting is concerned. Ten or twelve days after the first molt, the male undergoes a second molt, bringing it to the propupal stage. This stage is distinguished from the true pupa chiefly by the less fully developed appendages, as shown by their enclosing sheaths. After eight or ten days in this stage, it changes to the true pupal condition, and a similar period is passed in this stage before emerging as an adult. The male, therefore, issues as an adult about sixty days from birth. The period will be from ten to twelve days less during the warmest part of the season, and extended as much as twenty or twenty-five days in winter. The female will begin depositing eggs about seventy-five days from birth, or fifteen days after fertilization by the male. Egg laying will continue for three or four weeks. The eggs hatch and young will emerge from the scale on an average of three months from birth; this again varying from ten or twelve days less in midsummer to a month or more in winter. After the female has deposited her quota of eggs, numbering from thirty to eighty, she dies, making the complete life cvcle from four months in summer to from five to six months in winter. 336 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. Lepidosaphes beckii. Development. Number examined. 0 s i • 5 (B - F 3 CO 3 o 38 a o Qi 3 o n 3 s £3 as 1 a o> CO a ! SB i a, ; *2 S3 2 ^ P'go 1 7 103 3-19-09 3-30-09 3-24-09 5-19-09 5-20-09 5-20-09 5-20-09 5-22-09 5-22-09 5-25-09 6-25-09 6-28-09 7- 1-09 7- 1-09 7-19-09 8-20-09 8-21-09 6-18-10 6-18-10 6-18-10 6-18-10 6-18-10 2-18-11 6- 8-11 erages _ 10 12 3 3 6-10 6-6 6-10 125... — 6-10 116 6-15 . 152 17 5 7-6 _. 153 6-18 6-18 _ 154 - - 6-26 7-1 7-8 7-16 8-16 155 162 52 37 46 28 21 36 7-21 7-24 £ -10 U 8-16 163 7 7-10 ... 6 6-14 8-18 166 167 7-6 6-30 7-6 . 8-18 199 6 1 3-6 3-9 3-9 206 _ 8-1 8-1 8-18 < c -16 -20 205 9-26 250 15 5 8-11 305 10-27 11-2 _. 11-30 308 __ 580 7-10 7-26 ... 7-17 .. 7-24 8-6 8-5 8-10 9-11 581 9-10 582 15 15 15 7 9 4 7-25 _. 8-14 583 7-17 7-24 9-9 584 8-7 5-6 7-30 60 9-11 3-6 6-30 26 days 4-17 -._ 7-25 50 days 36 7-13 days 7-20 __ 44 52 65 75 Summary av 90 SEASONAL HISTORY. Since the time required for the life cycle, from young to young, during the summer months is about three months and in winter may be prolonged a month or more longer, the number of generations will not exceed four. In fact, during ordinary seasons there will be but three generations, with probably a partial fourth. From May to October, inclusive, they will go through their development in three months, or slightly less, so that there will be two full generations dur- ing this period. A third will get fairly well started before the colder wet weather of January and February. But the development of this generation will be prolonged by the lower temperature so that it mayl require four months for the cycle. This will bring it into March again, when at best the fourth generation will only be partially developed by the last of April. During May, and also in June, young scales begin appearing in large numbers, which is the first definite spring hatch. It is altogether likely that in many cases these are the progeny of the third generation. During the remainder of the summer young scales will be found continuously in considerable numbers. Eggs will be found at any season of the year, but during the winter months the young will appear mostly during the warmer periods. Bulletin 22G] THE purple scale. 337 PARASITE. Practically nothing has been written about any parasites of the purple scale in California. This scale has been considered to be freer from parasites than any of the other citrus fruit scales. While this, in general, is true, yet in certain places the purple scale is as heavily parasitized as the red or yellow, and the parasite in question has been known to occur in the State since 1891. But in many sections of the citrus belt where the purple scale occurs, little or no trace of this parasite will be seen. In sections, as Whittier, where fumigation is so generally practiced as it was in 1910 (98 per cent of the acreage) there is no doubt about its effect on the parasites. In considerable purple scale material collected from this vicinity during the past two or three years, there have been but occasional instances where parasites were obtained. But just outside the Whittier section, where trees infested with purple scale had never been fumigated or sprayed, as high as 30 per cent or 40 per cent of the scales at one time were found parasitized. This same fact holds true for the yellow scale parasite, for it is the same parasite that attacks both scales. Yellow scale material has fre- quently been obtained from sections where fumigation is generally prac- ticed, but none or few parasites were secured. But yellow scale material taken from Santa Barbara County, and in the northern sections where no fumigation is practiced, had a considerable percentage of the scales parasitized in many instances. Aspidiotiphagus citrinus Craw.* Aspidiotiphagus citrinus Craw, is the only parasite that we have taken thus far from the purple scale. This is the insect referred to above, and, while occurring in certain limited localities in considerable numbers, it is not common throughout the purple scale belt. This is a strictly internal parasite and attacks the scale only between the first and second molt. The scale has shed its first skin and approaches very nearly the time when it should cast its second skin. But thus far no instance has been observed where the scale had actually molted the second time. The egg is deposited within the insect and there hatches a very minute, white larva, with a tail-like appendage. This is afterward lost, and as the larva becomes mature it is about .85 mm. long and .35 mm. wide, tapering slightly toward the anterior and more strongly toward the posterior end. It pupates within the scale, the pupa at first being white or light colored but later turning very dark. The adult makes its way out through a circular exit hole in the posterior one third ♦For a more detailed account of this parasite, see Cal. Exp. Sta. Bull. 222. 338 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. of the scale, these being found only in the partly grown scales. The age of the scale when grown is stopped by the effects of the parasite, judg- ing entirely from the condition of the scale, appears to be about forty or forty-five days, when the second molt would occur in about fifty or fifty-five days. During the past two years a large number of these para- sites have been found issuing in December. This may be on account of the fact that the scales are, or have been, in the proper stage for attack. PREDACEOUS ENEMIES. The several species of native Coccinellidce, together with the larva of Chrysopus and Hemerobius, may all attack the purple scale as well as other scale insects. But the one Coccinelid that has been seen most frequently attacking the purple scale is Rhizobius lopantlice. This species also occurs commonly on the red scale. The larva of this beetle is distinguished by having rectangular areas of light gray on the other- wise dark dorsal surface. When full grown it is 4 mm. long and about 1 mm. wide. The adult beetle measures from 2 to 2\ mm. in length, and is black in color with a strong metallic luster. Scymnus marginicollis Mann, is another species that is often found with the purple scale. This beetle is similar in size to that of R. lopan- thce, but is of a dull black color instead of the metallic bronze-like luster of that of lopanthce. RELATED SPECIES. Aside from the species beckii, there are three others recorded from California as belonging to the genus Lepidosaphes. These are L. gloveru Pack., L. idmi Linn., and L. crawii Ckll. L. crawii has been recorded only from the oak and Elceagnus, and is therefore of no economic importance. L. ulmi is the common and widely distributed oyster-shell scale and occurs on many deciduous fruit trees. In the shape and appearance of the scale covering, it closely resembles the purple scale, but if the insect itself be examined it is readily distinguished by the fact that the lobes are not serrate as in the case with L. beckii, L. gloverii or Glover's scale is the other member of the genus that \s primarily a citrus fruit scale. It has been only rarely met with in California, while in Florida it is of very common occurrence. This scale covering is much more linear in shape than the purple and is not so often curved. The distinguishing characters of the insect itself are that the lobes are pointed and are not serrate. Bulletin 226] THE purple SCALE. 339 BIBLIOGRAPHY. The following is the bibliography of Lepidosaphes beckii that has appeared since 1903, according to Mr. E. R. Saccer of the Bureau of Entomology, who has kindly compiled it for this bulletin. Lepidosaphes beckii (Newn.). Theobald: 1st Rep. ec. Ent. Br. Mus. p. 133 (1903). Description, hosts, distribution and remedies. Marlatt, C. L. : Can. Ent. XXXV, p. 82 (1903). Simply a note. Coleman, G. A.: Jn. N. Y. Ent. Soc. XI, p. 83 (June, 1903). Hempel, A.: Bol. Agr. Sao Paulo, V, p. 322 (1904). Description, host, location, etc. Sanders, J. G. : Proc. Ohio Ac. Sci. IV (2). Sp. papers 8, p. 73 (1904). fig. 41. Bibliography and description. Craw, A. : Rep. Div. Entom. Hawaii Bd. Ag. & Forestry Dec. 31, 1906. pp. 143 and 151. Editor: Agric. News. West Ind., V, 99. p. 42 (1906). Del Guercio: Boll, del Min. d'Agr. Indust. and Comm. V. 3, p. 267 (1906) (Fig). Description, distribution, etc. Kotinsky, J. : Rep. Div. Entom. Hawaii for yr. ending Dec. 31, 1905. p. 139. Geoffroy, A.: L'Agricultura Ligure Anno VI. Feb. 15, 1906, pp.. 51-52. Herrera, A. L. : Bol. d. 1. Com. de Parasitologia Agric. Tomo. Ill No. 1, pp. 189-92 (1906). Draper, W. : Notes of the Injurious Scale Insects of Mealy Bugs of Egypt (Cairo), 1907. p. 10. Green, E. E. : Trans. Linn. Soc. of London, vol. XII. Pt. 2. Dec. 1907. p. 203. Recorded from Seychelles, Mauritius, India, Ceylon, Japan, Australia, Tasmania, New Zealand, Fijii, Hawaiian Islands, Java, West Indies, United States of America, Madeira, Africa, Europe. Ehrhorn, E. M. : 2d Bien. Rep. Com. Hort. State of Cal. 1905-06. pp. 23 and 224. Hempel, A. : Consultas attendidas Bol. da Agr. Estado de Sao Paulo, 8 ser. 1907, p. 280. Merely a note. Lepidosaphes beckii (Newn.). Autran, E. : Bol. del Min. Agr. vol. VII. No. 3. p. 154. 1907. Carnes, E. K. : 2d Bien. Rep. Com. Hort. State of Cal. 1905-06 (1907), pp. 217-18. Leonardi, G. : Estratto dal Bollettino del Laboratorio di Zoologia generale e agraria della R. Scuola Superiore d'Agricoltura in Portici, vol. Ill, July 15, 1908, pp. 190-91, figs. 62-64. On olives in Sicily. Howard, C. W. : Transval Ag. Jn. vol. VI, No. 22, Jan. 1908, p. 271. Fig. On all citrus fruits ; also fig. croton, and oak. Ehrhorn, E. M. : Proc. of 33d Fruit Grow. Conv. of Cal. p. 151. Sacramento (1908). Cook, A. J.: Off. Rep. 34th Fruit Grow. Conv. of Cal. p. 50. Sacramento (1908). Tower, W. V.: Ann. Rep. P..R. Agr. Exp. Sta. p. 23. San Juan (1908). On orange in Porto Rico. Newstead, R. : R. Quarterly Jn. Liverpool Univ. Vol. Ill, No. 6. p. 12, Jan. 1908. Cook, M. T.: > Estacion Central Agron. de Cuba, Feb. 1908. p. 22. Home, W. T. : S Common in Cuba. Marchal, P.: Mem. Soc. Zool. France, xxii, 1 and 2, p. 181 (1909). 3— bul226 ^40 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. Aymes and Trabut: Bui. Agr. de Alg. et del Tunisie, xiv, 9, pp. 222-223. (1908). Fig. Kirk. T. W. : ) Cockayne, A. H. : \ Am' Rep' N> Z' Dept- Agr* Div- BioL and Hort p" 283 (1909>- Essig, E. O. : Bull. No. 2. Claremont Pomological Club. Apr. 15, 1909. HaddeenWE.f' : \°^ Ent- xii' S- » 2" <1009>- Carnes. E. K. : 3d Biennial Kept. Com. Hort. Cal., p. 25 (1909). Dean. Geo. A.: Trans. Kans. Acad, of Sciences XXII, p. 275 (1909). Woodworth, C. W. : Jn. Econ. Entom. Vol. II, No. 5, p. 359. Oct. 1909. Barber, T. C. : Jn. Econ. Entom. vol. 3, No. 5, p. 425. Oct. 1910. Recorded on orange, Citrus trifoliata and Camellia japonica from Audubon Park, New Orleans, La. STATION PUBLICATIONS AVAILABLE FOR DISTRIBUTION. REPORTS. 1896. Report of the Viticultural Work during the seasons 1S87-93, with data regard- ing the Vintages of 1894-95. L897. Resistant Vines, their Selection, Adaptation, and Grafting. Appendix to Viti- cultural Report for 189 6. 1902. Report of the Agricultural Experiment Station for 1898-1901. 1903. Report of the Agricultural Experiment Station for 1901-03. 1904. Twenty-second Report of the Agricultural Experiment Station for 1903-04. BULLETINS. Reprint. No. 128 133 147. 149. 153. 159. 162. 165. 167. 168. 169. 170. 171. 172. 174. 176. 177. 178. 179. 180. 181. 182. 183. 184. 1S5. 186. 187. 188. 189. 190. 191. Endurance of Drought in Soils of the Arid Regions. Nature, Value, and Utilization of Alkali Lands, and Tolerance of Alkali. (Revised and Reprint, 1905.) Tolerance of Alkali by Various Cultures. Culture work of the Sub-stations. California Sugar Industry. Spraying with Distillates. Constribution to the Study of Fermentation. Commercial Fertilizers. (Dec. 1, 1904.) Asparagus and Asparagus Rust in California. Manufacture of Dry Wines in Hot Countries. Observations on Some Vine Dis- eases in Sonoma County. Tolerance of the Sugar Beet for Alkali. Studies in Grasshopper Control. Commercial Fertilizers. (June 30, 1905.) Further Experience in Asparagus Rust Control. A New Wine-cooling Machine. Sugar Beets in the San Joaquin Valley. A New Method of Making Dry Red Wine. Mosquito Control. Commercial Fertilizers. (June, 1906.) Resistant Vineyards. The Selection of Seed-Wheat. Analysis of Paris Green and Lead Arsenic. Proposed In- secticide Law. The California Tussock-moth. Report of the Plant Pathologist to July 1, 1906. Report of Progress in Cereal In- vestigations. The Oidium of the Vine. Commercial Fertilizers. (Janu- ary, 1907.) Lining of Ditches and Reservoirs to Prevent Seepage and Losses. Commercial Fertilizers. (June, 1907.) The Brown Rot of the Lemon. California Peach Blight. No. 192. 193. 194. 195. 197. 198. 199. 200. 201. 202. 203. 204. 205. 206. 207. 208. 209. 210. 211. 212. 213. 214. 215. 216. 217. 218. 219. 220. 221. 222. 223. 224. 225. Insects Injurious to the Vine in California. The Best Wine Grapes for Cali- fornia ; Pruning Young Vines ; Pruning the Sultanina. Commercial Fertilizers. (Dec, 1907.) The California Grape Root-worm. Grape Culture in California ; Im- proved Methods of Wine-mak- ing; Yeast from California Grapes. The Grape Leaf-Hopper. Bovine Tuberculosis. Gum Diseases of Citrus Trees in California. Commercial Fertilizers. (June, 1908.) Commercial Fertilizers. (Decem- ber, 1908.) Report of the Plant Pathologist to July 1, 1909. The Dairy Cow's Record and the Stable. Commercial Fertilizers. (Decem- ber, 1909.) Commercial Fertilizers. (June, 1910.) The Control of the Argentine Ant. The Late Blight of Celery. The Cream Supply. Imperial Valley Settlers' Crop Manual. How to Increase the Yield of Wheat in California. California White Wheats. The Principles of Wine-making. Citrus Fruit Insects. The House Fly in its Relation to Public Health. A Progress Report upon Soil and Climatic Factors Influencing the Composition of Wheat. Honey Plants of California. California Plant Diseases. Report of Live Stock Conditions In Imperial County, California. Fumigation Studies No. 5 ; Dos- age Tables. Commercial Fertilizers (Oct. 1911). The Red or Orange Scale. The Black Scale. The Production of the Lima Bean. Tolerance of Eucalyptus for Alkali. CIRCULARS. No. 1. Texas Fever. 7. Remedies for Insects. 9. Asparagus Rust. 11. Fumigation Practice. 12. Silk Culture. 15. Recent Problems in Agriculture. What a University Farm is For. 19. Disinfection of Stables. 29. Preliminary Announcement Con- cerning Instruction in Practical Agriculture upon the Univer- sity Farm, Davis, Cal. 30. White Fly in California. 32. White Fly Eradication. 33. Packing Prunes in Cans. Cane Sugar vs. Beet Sugar. 36. Analyses of Fertilizers for Con- sumers. 39. Instruction in Practical Agricul- ture at the University Farm. 46. Suggestions for Garden Work in California Schools. 48. Butter Scoring Contest, 1909. 50. Fumigation Scheduling. 52. Information for Students Con- cerning the College of Agricul- ture. No. Some Creamery Problems and Tests. Farmers' Institutes and Univer- sity Extension in Agriculture. Experiments with Plants and Soils in Laboratory, Garden, and Field. Butter Scoring Contest, 1910. University Farm School. The School Garden in the Course of Study. How to Make an Observation Hive. Announcement of Farmers' Short Courses for 1911. The California Insecticide Law. Insecticides and Insect Control. Development of Secondary School Agriculture in Cali- fornia. The Prevention of Hog Cholera. The Extermination of Morning- Glory. Observations on the Status of Corn-growing in California. Grains Recommended for Trial.