5TATL HORTICULTURAL COMMISSION LLLWOOD COOPER, Commissioner BUG V5. BUG Nature s Method of Controlling Injurious Species BY JOHN I5AAC Reprinted from the First Biennial Report of the State Horticultural Commissioner. 5ACRAMLNTO W. W. SHANNON, 1906 5UPT. STATL PRINTING ^ ^^ n CALIFORNIA 5TATL COMMISSION OF HORTICULTURL. ELLWOOD COOPER JOHN ISAAC ED. M. EHRHORN.- E. K. CARNES O. E. BREMNER ... CHAS. T. PAINE.--. .Commissioner KSaiita Barbara Secretary San Francisco . Deputy M ou n tain View . Assistant Riverside Assistant Santa Rosa Assistant Redlands GERTRUDE BIRD Stenographer Sacramento OFFICE: Room 41, State Capitol, Sacramento. Branch Office, Room 11, Ferry Building, San Francisco. ^Hn 30 '^0: !^ BUG VS, BUG. By JOHN ISAAC. A somewhat siiuill and unpretentious exhibit was that made at the St. Louis Exposition by the California State Commissioner of Horti- culture, but it was one that attracted a great deal of attention, especially among scientific men and the more intelligent class of orchardists and farmers who visited that great exposition. This exhibit consisted of a very complete and well-arranged collection of the various insect friends to which California owes so much of her prosperity, and which are ever and continuously working in our interest. Many of these insects are exceedingly minute, so much so as to be practically out of the range of the naked eye. To overcome this difficulty they were displayed behind magnifying glasses of sufficient power to enable them to be seen, while descriptions of them and the work they are doing for our State were made in plain language. The result of this has been a great deal of inquiry from Eastern sources as to our beneficial insects and our Cali- fornia method of fighting bugs with bugs. To answer these inquiries, as well as to give our own people a wider knowledge of Avhat our insect friends are doing for us, the following pages have been prepared. Below is a list of the different insects exhibited at the St. Louis Exposition by this Commission : PREDACEOUS COCCINELLID^. Beneficial Insects. Host Insects. Vedalia cardinalis Cottony Cushion Scale (Icerya purchasi). Novius koebelei Cottony Cushion Scale (Icerya purchasi). Novius bellus Cottony Cushion Scale (Icerya purchasi). Vedalia sp. (black) . Cottony Cushion Scale (Icerya purchasi). Rhizobius ventralis -.- Black Scale (Saisseta oleoe). Rhizobius ventralis, larvcv.. -Black Scale (Saisseta olese). Orcus australasia Black Scale (Saisseta olete). Orcus chalybeus Yellow Scale (Chrysomphalus [Aspidiotus] citrinus). Rhizobius toowoombce. . . San Jk>se Scale (Aspidiotus perniciosus). Scymnus vagans Red Spider (Tetranychus telarius). Rhizobius debilis _ Various scale insects. Cryptolaemus montrouzieri .-Mealy Bugs (Pseudococcus [Dactylopius] sp.). Hyperaspis lateralis Cypress Mealy Bugs (Pseudococcus ryani). Exochomus pilatii Various scale insects. Chilocorus bivulnerus... San Jose Scale (Aspidiotus perniciosus), and others. Coccinella sanguinea Various scales and aphids. Coccinella californica .-.Various aphids. Coccinella abdominalis Various aphids. Coccinella oculata Various aphids. Hippodamia ambigua Various aphids. Hippodaniia convergens Various aphids. 4 CALIFORNIA STATE HORTICULTURAL COMMISSION. PARASITIC HYMENOPTERA, DIPTERA, ETC. Beneficial Insects. Host Insects. Scutellista cyanea Black Scale (Saisseta olese). Dilophogaster californica . ...Black Scale (Saisseta olese). Hymencyrtus crawii ._--- ... Black Scale (Saisseta oleoe). Apheliiuis mytilaspidis Black Scale (Saisseta ole*). Aphelinus fuscipennis San Jos6 Scale (Aspidiotus perniciosus). • Aspidiotophagus citrinus.... Yellow Scale (Chrysomphalus [AspidiotusJ citrinus) and San Jos6 Scale (Aspidiotus perniciosus). Pteroraalus puparum Internal parasite of the Cabbage Buttertiy (Pieris rapa^). Comys fusca Brown Apricot Scale (Eulecanium armeniacum). Encyrtus flavus _ Soft Brown Scale (Lecanium [CoccusJ hesperidum). Coccophagus lecani Soft Brown Scale (Lecanium [Coccus] hesperidum). Coccophoctonus sp. ...Yellow and Red scales. Eupelmus mirabilis Internal parasite of the Katydid (Microcentrumretinervis). Braconid sp Parasite of Cutworm. Anastatus sp Egg parasite of Tent Caterpillar. Tachnia fly Internal parasite of Cabbage Butterfly (Pieris rapre). _ Internal parasite of Lecanium robinarum. Aphelinus sp. ... Internal parasite of Aphis. Somewhere about the year 1868, a California nurseryman in San Mateo County, not far from San Francisco, imported some lemon trees from Australia. There was nothing unusual about this, nor was there apparently anything unusual on the trees themselves; nevertheless that importation cost the State of California millions of dollars and came near destroying one of the most important of its fruit industries, for on those trees, unseen and unnoticed by any one, were some of the young of the now well-known cottony cushion scale (Icerya purchasi) . These soon reached their mature stage, and still no notice was taken of them ; they were regarded merely as a curious object when noticed, and it was never dreamed that they were the commencement of one of the most terrible pests that California fruit-growers have ever known. The insects increased in numbers, but not being in a fruit section, and their depredations being confined largely to ornamental stuff, they were dis- regarded. Soon afterwards a Los Angeles nurseryman and florist secured some of the imported stock, with the imported pest, and so it was introduced into Southern California. Here conditions were better suited to it than even in the section where it had first obtained a foot- ing in the State, and it spread much more rapidly. Soon it got into the orange orchards. Here conditions seemed perfect, and in a very short time it had spread to an alarming extent. Orchards in which it had become firmly established were covered with it until they looked as though they had been exposed to a severe snowstorm. It was soon found in remote sections, and in a short time appeared to have taken possession of the whole country. Nor did it confine itself to the orange trees; many varieties of fruit and a great quantity of ornamental plants fell beneath its attacks. It even found its way to forest trees, and for some time it looked as though it would reduce the whole countrj^ BUG VS. BUG. O to a desert. Orange-growers were in despair. From eight thousand carloads, shipments dropped to six hundred in one year. Every pos- sible remedy was tried, but none was found effective, and even the most costly served only to temporarily check the spread of the pest. Orange- growers were digging out and burning their trees to get rid of the pest, but even this did not avail, for had all the orhards been destroyed there was sufficient wild stuff' to keep it spreading. In 1888 the National Government made an appropriation for the purpose of advancing the American interests at the Melbourne Expo- sition, and the appointment of the late Hon. Frank McCoppin as chairman of the commission to forward said interests w^as the nucleus of California's first eff'ort in the search for natural enemies of orchard pests. McCoppin 's friends in the orange district where this pest had caused such terrible losses urged that he should do something to save the orange industry. Correspondence was opened with the Hon. Thomas F. Bayard, Secretary of State, and through him, with the Department of Agriculture and the Entomological Division of that Department. This resulted in the sending of Albert Koebele, who dis- covered the Vedalia cardinalis, with the commission. While there were others in the State who were convinced of the parasitic theory and enthusiastic in their eff'orts to bring about the investigation, there was no available money until the above opportunity presented itself. This discovery of a small ladybird known as the Vedalia cardinalis started California on her present course of fighting bugs with bugs, and no doubt this will continue until every insect pest that disturbs plant life and its fruits will be overcome by natural insect enemies, even if it should require traversing the very ends of the earth. It is to be hoped that other states, and the National Government, will take up this work and thereby save hundreds of millions of dollars' loss that is now borne by the cultivators of the soil. This ladybird was collected and forwarded to California and dis- tributed all over the State wherever the scale had made its appearance. Nearly, if not quite, all of the injurious pests of any section are intro- duced species, and in every case they have been introduced without their checks, for in its native habitat every pest, in fact every form of life, has some other form of life which preys upon it and prevents it from becoming redundant. Now, when any such form is removed to a new section, where it has no natural enemies, there is nothing to stop its unlimited spread, and as insects propagate more rapidly than any other form of animal life, without some check they would soon overrun everything within reach. These checks are usually other insects, and they are divided into two general classes— the predaceous class, or those which devour their prey from the outside, the most important among which is the great ladybird family, and the parasitic class, or those which 6 CALIFORNIA STATE HORTICULTURAL COMMISSION. work in or on the body of their host. These latter are often microscopic, or very nearly microscopic, in size, but are among the most effective of our insect friends. Usually each predaceous or parasitic insect attacks but one kind of insect ; each has its own particular form of food and will touch no other. The Vedalia^ for instance, lives wholly upon the cottony cushion scale, and if it can not get this, it will starve before it will touch any other form of food; so that, in searching- for the enemies of our destructive^ insects, it is necessary to find just the right one. It is a fact well known to all entomologists, that in their native homes, while insects are sometimes very troublesome, and in some s^^ctions exiftt in unusual numbers, they never become the serious pests that they do when they are removed to a new country where their cheeks 'do not exist. Usually in their native homes they are rather rare than otherwise. So when it is known that any pest is especially severe in any section, as, for instance, the San Jose scale (Aspidiotus peruiciosus) over a great part of the Eastern States, it is very certain that it has been introduced there, and in order to find its check, we must find its native home, where it is scarce, and then we must find what agency is keeping it down. Some- times our native parasites will adapt themselves to the introduced species, as has been the case in California with the San Jose scale. This pest was as great a terror to our growers some twenty years ago as it now is over a great part of the Eastern States ; but one of our native parasites, ihe Aphelimis fuscipennis, adapted its taste to it, and finding in the San Jose scale a suitable food supply, it increased with almost unprecedented rapidity until it overtook the scale, and to-day this scale is no longer a pest in the California orchards. It is true that it occasionally makes its appearance in remote sections, but never to any dangerous extent, and the little parasite soon overtakes it and reduces it below the danger line. So little regard is paid to the San Jose scale in California now, that we never recommend any action against it. Spraying is still carried on, but this is more for the purpose of keeping the trees clean and healthy than for the purpose of getting rid of the San Jose scale. Before this parasite did such eit'ective Avork, California orchardists were having very much the same experience that their Eastern brethren are having now, and trees by thousands were dug out and destroyed in order to get rid of the scale. It is to be hoped that the days of this terrible pest in the Eastern orchards are numbered, for it has been discovered that the same parasite which hns freed the California orchards is now at work there, and in a report made by Prof. W. G. Johnson, when entomologist of Maryland, he says: Since we assumed chai-go of the State work in Maryland, we have collected the San Jose scale on various food plants and inclosed infested twigs, about four inches in length, in glass cylinder tubes, open at both ends ; the ends were closed with cotton, and if any parasites existed upon the scale, they were easily detected and mounted for BUG VS. BUG. 7 study. Only upon rare occasions have we taken more than a half-dozen specimens from a single tube. This experience has been repeated year after year until the fall of 1899. • * * Last fall, however, I discovered a new locality for Aphelinus fuscipcnnis, near Easton, Talbot County, in an infested orchard along the Miles River. The orchard contained a miscellaneous variety of fruits, and all the trees were quite seriously infested with the San Jose scale. Instructions have been given the owner to cut them down as soon as possible and burn them. A quantity of small branches infested with scale were brought to the laboratory and inclosed in breeding tubes. Much to my surprise, these tubes were swarming with parasites a few days later. From one tube J, 114 specimens of Aphelinus fuftcipennis were taken, while a second tube gave 432. a third 1,478. and a fourth more than 1.000, but owing to an accident the count in the case last mentioned was not exact. The California method of fighting insect pests is to use the most efficient artificial means while we have to, and to this end we apply all sorts of known washes, dips, and fumigation, but, while so doing, we realize that these measures are very cumbersome, costly and inefficient, and that nature has provided a better way, and it is of this way that we avail ourselves. We endeavor to trace back the course traveled over by our destructive pests, to trail them to their native lair, and there we will find their check. This check, whether it be a parasitic or a preda- ceous insect, or both, as sometimes found, we secure, introduce, and breed, with the greatest care, in our insectary, where it becomes accli- mated in its new home, and as it propagates it is sent into those sections where the pest upon which it is to prey is most prevalent. This method has been found so effective that we have now very few really trouble- some orchard pests, the worst at the present time being the codling- moth, and for this we hope to find a natural check, and are now working toward that end. It must not be supposed from this that there are no insect pests in California. AVe have been importing these pests from all parts of the world for half a century past and have had representatives from all parts of the world, and have them still, for when an insect once obtains a foothold, its eradication is practically impossible, but by introducing its natural enemy, we offset one against the other, and give ourselves no further uneasiness as to the outcome. The pests may do some damage, they may break out in sections in unusual numbers for a time, but invariably they are reduced below the line of serious damage shortly by the natural means, and it is done more effectivelj^ and permanently than can be done by any artificial method. In an address before the fourteenth annual meeting of the Association of Economic Entomologists, Prof. C. L. Marlatt gave an account of a trip he had made to Japan and China in search of the native home of the San Jose scale, and in speaking of its discovery there he alluded to para- sites which he found working upon it, and which are the same species which have done such good work on this pest in California. He said: The apple industry of Japan is of recent origin, say within the last thirty years; most of the stock has been obtained from California, and as a rule was more or less EXPLANATION OF PLATE I. Fig. 1. Novius Iwebelei, Olliff; Koebele's ladybird. Male; enlarged, la. Novius koehelei. Male ; natural size. Ih. Novius koehelei. Female; natural size. Ic. Novius koehelei. Larva; enlarged. 2. ^' Black Vedalia." Enlarged. 3. Novius hellus. Beautiful ladybird; enlarged. 4. Novius (Vedalia) cardinalis, Mulsant; Australian ladybird; 4a. Novius {Vedalia) cardinalis. Natural size. 4&. Novius (Vedalia) cardinalis. Larva ; enlarged. 5. Lestophonus icerya. Dipterous parasite of the cottony cushion scale; enlarged. 5a. Lestophonus icerya. Natural size. 6. Ophilosia crawfordi. Hymenopterous parasite of the cottony cushion scale; enlarged. 6a. Ophilosia crawfordi. Natural size. 7. Twig infested with cottony cushion scale ; natural size. 7a. Icerya purchasi crawii, Cockerell. Ih. Icerya purchasi maskelli. California State Commission OF Horticulture.. PLATE I BUG VS BUG. Ti-iK eeneficij^l iri sects THAT SAVEE) THE CITRUS FR-JIT Ii\^DUSTR-l- Or CALIFORNiA. BUG VS. BUG. 9 infested with San Jose scale when received. Throughout this region the San Jose scale was found scatteringly in all orchards and in all gardens. In Aomori and vicinity it is doing no very great damage in any of the orchards, but in some of the small gardens and especially in one or two neglected ones in the city of Aomori, it was as abundant on particular trees as it often is in America. At the first investi- gation no evidence of parasitism was seen, but from later collections two of the parasites which attack the scale insect in America were raised in great numbers from infested branches collected at Aomori. These as determined by Dr. Howard are ApheliriHS fnscipcnni.'i, How., and Aspidiotophogus citriniis. Craw, the latter being the more numerous. This latter parasite is the true internal parasite of the Japanese yellow orange scale. The San Jose scale is not a native of Japan, so it is evident that this little parasite adapts itself to the introduced variety, which is a near relative of the yellow scale upon which it is generally found. So effective has this work of introducing beneficial insects and encour- aging native parasites been, that we have practically reduced all the worst of our scale pests and very many other destructive insects below the danger line. Among the many beneficial insects which are now at work in our State, and the pests which they are at work upon, and most of which they keep in control, we name the following : COCCINELLID^. Vedalia eardinalis, Mulsant. (Plate I, Figs. 4, id, if>.) This is connnonly known as the "Australian ladybird," from the fact that it was imported from Australia in order to work upon the cottony cushion scale (Icerya purclum, Maskell). As stated above, this pest had obtained such a foothold in our orange orchards that the citrus industry of California was threatened. The fact that the cottony cushion scale came from Australia, where it was not a pest, was sufficient proof that there was some \Qvy efficient check at work upon it there, and investiga- tion by Albert Koebele discovered this little beetle. The orange-growers of Los Angeles County, especially, had a very expensive experience with this scale. As it had spread into the wild bushes and trees, extermina- tion by artificial means was out of the question. Now the scale is no longer a pest. When it appears in an orchard the owner is supplied with a colony of Vedalia. During the summer the transformations of this ladybird are very rapid. From the q^^, through the larva and chrysalis, to the perfect beetle, takes only twenty-one days. Of course, the larvae are the most active feeders. AVhen short of feed, the larvae will attack each other, but no matter how^ hungry they are they will not eat any other species than the cottony cushion scale. This ladybird breeds throughout the year. Novius koebelei, Olliff (Koebele's ladybird). (Plate I, Figs. 1, la, lb, Ic.) This is another effective enemy of the cottony cushion scale 2— BII 20 CALIFORNIA STATE HORTICULTURAL COMMISSION. and does as good work as the Vedalia. The latter, however, was first introduced, and its reputation became so great that all others were over- shadowed by it. The Novius koehelei, hoAvever, has proved itself equally as prolific and quite as voracious a devourer of the cottony cushion scale as its companion. This ladybird is also an introduced species, having been sent from Australia for the State Board of Horticulture by Mr. Koebele on his second trip to that country. The illustrations give a good idea of this beautiful and active little ladybird. It feeds upon the cottony cushion scale {Icerya purchasi), searching out the solitary scales even better than the Vedalia. It passes through its different stages in about the same time as the latter. FIG. 1. Xovius kot'bek'i, mak', enhirSLMl. FIG. 2. Novius koebelei, female, enlarged. Novius bellus (Beautiful ladybird). (Plate I, Fig. 8.) This is also an Australian species, having been introduced into California from that country by Mr. George Compere. It is one of the several coccinellid enemies of the cottony cushion scale, and has done very excellent work upon that pest. It has been generally distributed over the State. Vedalia sp. (Plate I, Fig. 2.) This is an unnamed species of Vedalia, from its color commonly known as the "Black Vedalia." It is also an Australian species, introduced by the State Board of Horticulture through Mr. George Compere, and is another of the coccinellids which prey upon the cottony cushion scale. Rhizobius ventpalis (Black ladybird). (Plate IV, Figs. 3, 3a, 86.) This is also an Australian ladybird, introduced by the State Board of Horticulture through Mr. Koebele, and is one of the natural enemies of the black scale {Saisseta [Lecanium] oleae) . This ladybird was intro- duced for work on tlie black scale, and was generally distributed by the State Board of Horticulture wherever that pest Avas found. It was one of the most promising of the many importations of beneficial insects and took hold of its work with a vigor that gave promise of soon extir- pating one of the worst of the California scale insects. Wherever it was introduced in the coast counties of the State, it increased with wonderful BUG VS. BUG. 11 rapidity and the scale as rapidly disappeared, and in those sections it j^till continues to do good work, but efforts to establish it in the interior counties have not met with as good success, the heat probably being too intense for the young larvie. This insect, however, is well established all over the State, and in many sections is as abundant as any of our native species. Wherever it is abundant, it is a chief factor in keeping in check the destructive black scale. • Opcus austpalasia, Boisd. (Six-spotted blue ladybird). (Fig. 3.) This is one of the most beautiful of the introduced species. Like most Obcos austhalasi/C. Boisd 2 Pupa enveloped in la FIG. 8. Orc-us australasia. of the latter, it is a native of Australia, and was imported from that country by the State Board of Horticulture through Mr. Koebele. It is an enemy of the black scale (Saisseta [Lecanium] oleae) , and is now well established in many parts of California, especially in the coast counties. The female is nearly one fourth of an inch in length, deep blue in color, with six orange red spots on the wing-covers. The male is similarly marked, but is a smaller insect. This species is a more general feeder than 0. cJialyheus. In Santa Barbara County it is bred on black scale, and in Alameda on the pernicious scale. It loves the sunshine, and is found more numerous toward the top and the outside branches of the trees in which it is established. The larva -aiid pupa resemble the same stages of Pilate's ladybird. Opcus ehalybeus, Boisd. (Steel-blue ladybird). (Fig. 4.) So named from its brilliant steel-blue color, which makes it a conspicuous object wherever it is found. This ladybird preys largely upon the yellow scale {Chrysoni- phalus [Aspidiofiis] ciiriniis, Coquillett), and also upon bens, enlarged. ^ the red scale (Chrysornphalus [Aspidiotus] aurantii, Maskell), which it consumes in great quantities. This was introduced into California EXPLANATION OF PLATE 11. Fig. 1. Encyrtus flaviis, Howard. Enlarged. la. Encyrtus flaws. Natural size. 2. Coccophagus lecani, Howard. Enlarged. 2a. Coccophagus leca^ii. Natural size. 3. Comys fusca, Howard. Enlarged. 8a. Comys fusca. Natural size. 4. Soft brown scale {Coccus [Lecanium] hesperidum, Linn.). On orange leaf. 5. Brown apricot scale {Eulecanium [Lecanium] armeniacum, Craw). On prune twig. 6. BroAvn apricot scale, showing exit holes of Comys fusca. California State Commission OF Horticulture. PLATE II BUG VS BUG. THE INTEHTIA:- P.^J?ASrTES THAT HOLD IN CKECi THE "soft BR-OWri SCALE" AJvEi THE "BROWN APRICOT SCALe' IIj CATTFOP.niA BUG VS. BIG. l:^ by the State Board of Horticulture some years ago and is now found established in many parts of the State. Rhizobius (toowoombse) lopantha. (Plate III, Fig. (>.) This little ladybird was formerlj^ described under the name of Scymmis margini- collis, but is identical with Rhizohius lopantha. Mr. Koebele sent this beetle about the same time that he introduced the Vedalia, but it wa.s found in the State previous to that. However, it has only been within the past few years that its value has been observed. It breeds from early spring until late in the fall. As comparcfl with the beetles the larvce are very large, they are light colored, with a lighter oblong scjuare on center of the back, and remain a long time in the larval stage, feed- ing voraciously. AVhen about to change to the chrysalis, they hide away under cobwebs, dry leaves, and other debris. The beetle is metallic black, with a brown thorax. They feed on Aspidiotus perni- ciosus, Chrysoniplialus (Aspidiotus) aurantii, Clirysompkalus (Aspidio- tus) citrinus. Aspidiotus hederae (nerii) , and occasionally on aphis. In San Diego County it is proving effective on purple .scale (Lepidosa- plies hechii). In alluding to the excellent work of this little beetle on the purple scale in the above named county, Mr. Allen, of Bonita. Avrites : With us the largest hatch of purple scale has usually been in May. So far this year I have not seen a single instance of purple scale hatching, nor can I find any live scale in an orchard adjoining us. every tree of which a year ago was literally alive with them. Since last .July this orchard has been to my knowledge thoroughly stocked with the Scynuius. though when they first entered it I can not say. As they undoubtedly came in large numbers their work has been rapid. , I sprayed only a small part of the ranch last summer, and there can be no question but that, except for the work of this parasite, our place would be teeming with the purple scale, whereas T have yet to see the first live one, and our fruit, from trees that used to be infested, is now coming off the tree clean. I believe this ladybird is also eating the yellow scale, because there is so much less of it on the fruit, but of this I am not yet sure. By September the efficiency of the purple scale parasite should be thoroughly estab- lished, for if any live eggs are left thej' must hatch before that time ; yet even now it seems to me that the work of the i^cymnns is second only to that of the Vedalin. and, considering the difference of the scales and the fact that the purple is so heavily armored, its work seems even moi'e remarkable. Seymnus vagans. This is one of the smallest of the ladybird family, but not one of the least important. It is an enemy of the red spider pest which is very general all over the world, and especially detrimental to almonds, prunes, and citrus trees. The long, dry seasons of California are favorable to the spread of this pest, which flourishes under arid conditions, and which has been especially troublesome here. This little ladybird was introduced from Australia by Mr. George Compere for the State Board of Horticulture. It was found to be veiy effective in checking the spread of the pest, and has been generally established in California. 14 CALIFORNIA STATE PIORTICULTURAL COMMISSION. Rhizobius debelis. This is another one of the introduced species of ladybirds which we owe to Australia. It is a scale-feeder and has been very generally distributed in the State. Cryptolgemus montrouzepi. (Fig. 5.) This is another of the Austra- lian coccinellidse. It is the natural enemy of the mealy bug {Pseudococcus [Dactylo- pius]). It has been introduced into the Hawaiian Islands, where this pest was so bad in the coffee plantations as to almost threaten the total destruction of the crop, and it has done such good work that the pest has been practically cleaned out. Suc- cessful efforts have also been made to estab- lish it in the coffee plantations of Centi'al America, where the mealy bug has also ap- peared in destructive numbers. FIG Cryptokumus inontrouzeri. eiihirge-H6' ^ifiiiiients*,- "twice-stabbed ladybird. " Natural size. 3a. Chilocorus hivulnerus. Larva. Natural size. 4. San Jose scale (Aspiodiotus perniciosus, Comstoek). Natural size. On pear twig. 5. Yellow .scale {Aspidiotus citrinus, Coquillett). Natural size. On orange leaf. 6. Rhizohius (toowoomhae) lopantha. Natural size. California State Commission OF Horticulture. PLATE # i^iTH.BRTTTPM ^HEV.BV. BUG VS BUG. THE FOUR SPECIES OF INSECTS THAT SUBDUED THE "SAN ^OSE SCALK" i^j^D "YELLOW SCALe" IN CALIFORNIA. BUG VS. BUG. 17 also feed upon aphids, young- scale, etc. The beetles vary somewhat in color; some are of a deep red, while others are of a dull browm, the markings, however, being uniform. Sometimes after ripe fruit has been punctured by birds or other agencies, the beetles of this species will be found upon it, sipping the moisture, and on this account they have been thought sometimes to be injurious. They are, however, among the most important of our insect friends. Hippodamia ambigua, Le Conte. (Figs. 7, 8, 9.) This is a very abundant native species. The adult beetle resembles the blood-red ladybird somewhat, but is narrow^er in proportion to its leng:th, and flatter. It is distributed over the w^hole State, and is often found in great numbers. It is an aphis enemy, and does' excellent work on the plum, apple, and woolly aphis. During the later fall months these insects may often be found in sheltered places in great masses, in which condition thev hibernate during: the colder months. FIG. Hippodamia ambigua. enlarged. FJU. 8. Hippodamia ambigua, pupa. FIG. 9. Hippodamia ambigua, •a. Eippoda larvi HYMENOPTERA. Seutellista eyanea, Motsch. (Plate IV, Figs. 1, la, 16, Ic.) This IS comparatively a new introduction into our State, having been secured from South Africa, where it was found to be a very effective worker on the black scale (Saisseta oleae) . In the short time it has been estab- lished among us. it has done most remarkable work, and, so far, promises to be as efficient a check for the black scale as the Vedalia has been on the cottonv cushion scale. Of its introduction, ^Tr. Craw writes : It was not until Prof. Charles P. Lounsbury, Government Entomologist of Cape Colony, called attention to the l^cutellista eyanea as an efficient enemy of the black scale in that country, that its true value was recognized. Through the efforts of the Hon. !