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Prof. Albert Koebele, of the entomological division of the Federal Department of the Interior-the Bureau of Entomology not yet having been established-was sent to Australia, to try to find a check for the pest in the country from which it had come. He discovered a natural foe of the cottony cushion scale in the l'edalia cardinalis, a beautiful little red and black ladybird; collected it in quantities, and forwarded it to California, where it was distributed wherever the pest had made its appearance. A little later he introduced another species, Novius koebelei; and some time afterwards Mr. George Compere, explorer for the California State Board of Horticulture. discovered and introduced Novius bellus and the Black Vedalia. These ladybirds, like all others of the numerous species-numbering perhaps two thousand-of the great family of Coccinelidæ, are predaceous in their habits, both the larvæ and the matured
VARIOUS SPECIES OF LADYBIRD AND THE PARASITES FROM WHICH THEY SAVED CALIFORNIA'S $20.000.000 CITRUS FRUIT CROP.
1-4b inclusive represent ladybirds and larvae: 5-7b, cottony cushion scale parasite; 7, twig infested with cottony cushion scale.
from 1888, the occasion being the ravages of an Australian pest introduced twenty years before. This was the cottony cushion scale, which for a time threatened the very existence of the orange growing industry. Groves that were badly infested presented the appearance of having been exposed to a severe snowstorm. From the orange trees the pest spread to hedges, shade trees, wild shrubbery and forests, until it was feared that vast areas of the State would revert to desert conditions. Shipments of oranges dropped from eight thousand car loads in one year to six hundred the next. Thousands of trees were cut down and Jurned, but the rest had been so widely scattered and had obtained so firm a footing upon wild vegetation that attempts to check its ravages, even by these heroic measures, were hopeless.
THE TRUE PARASITE AND ENEMY OF THE BLACK SCALE-SCUTELLISTA CYANEA AND RHIZOBIUS VENTRALIS.
1-2. scutellista cyanea: 3-3b, rhizobius ventralis
insects pouncing upon and devouring the scale insects and plant lice that form their natural food. Other foes of the cottony cushion scale, also introduced from Australia, are a dipterous parasite, known as Lestophonus icerya, and a hymenopterous parasite, Ophilosia crawfordi. These deposit their eggs in the grub of the injurious insect; and when the young develop they feed upon the tissues of the host, killing it in embryo. Through the operations of these predaceous ladybirds and internal parasites, the cottony cushion scale was brought under complete subjection. It is no longer feared as a pest or regarded as a source of danger, so that in describing these species as the "beneficial insects that saved the citrus fruit industry of California, the State Commission of Horticulture indulges in no hyperbole or exaggeration. If anyone doubts whether it was worth while, it is sufficient to say that the citrus fruit crop of the State amounts to something like 35,000 carloads annually, worth $40,000,000 in the Eastern markets, or half that when
FOUR SPECIES OF INSECTS-1. 2. 3. AND 6-THAT SUBDUED THE SAN JOSE SCALE-4-AND THE YELLOW SCALE-5. 1. aspidiotophagus citrinus; 2, aphelinus fuscipennis; 3. chilocorus bivulnerus: 3a, larva of same; 6. rhizobius lophantha.
THE INTERNAL PARASITES-1, 2, AND 3-THAT HOLD IN
1, encyrtus flavus: 2. coccophagus lecani;
packed ready for shipment to those markets.
The successful fight waged by imported insect allies against this terrible. menace to the citrus fruit industry convinced Californians that the scientific method of combating insect pests was to pit one form of insect life against another-to employ bugs for fighting bugs; and to that end the State Insectary was established. In 1891, the state legislature made its first appropriation of funds for a systematic search for beneficial insects a search that Mr. George Compere, explorer for the California State Commission of Horticulture and for the entomological department of West Australia, has prosecuted in every quarter of the globe.
It is conservatively estimated that the minimum tribute annually levied by insect hosts upon American farmers is not less than ten per cent. of everything pro
Shipment of 2,000,000 ladybirds from California's State Insectary to the melon fields of the Imperial Valley.
duced from the soil, and that the annual havoc wrought by forest fires is less than the damage to forest growth for which insects are responsible. The checking of insect depredations, then, constitutes a problem in national conservation of far greater moment than many of the local conservation issues that have occupied the attention of legislators and of the public. Secretary James Wilson, of the Department of Agriculture, estimated the value of the farm crops of the United States for the year 1909 at $8,876,000,000. But before the farmer gathered his harvest, the insect armies exacted a toll that reduced the total by at least $900,000,000!
California's elaborate and efficient organization for fighting insect foes is under the supervision of State Commissioner of Horticulture, J. W. Jeffrey. It is plainly as important to prevent the
introduction of new pests as it is to find means of suppressing the old. So a Quarantine Division is maintained, in charge of Deputy Commissioner Dudley Moulton, with headquarters at San Francisco. Ironclad horticultural quarantine laws require that transportation companies, corporations and individuals bringing fruits, plants or bulbs into the State give notice to the quarantine officials, so that an inspection may be made. No vessel is permitted to enter any port in the State without having its cargo, even to the passengers' baggage, rigidly examined by the horticultural quarantine inspectors. Every tree, plant, bulb and package of fruit is taken possession of by these officials and carefully examined. Those found free from the suspicion of insect pests are promptly passed, and others are either fumigated or burned, as circumstances make necessary. Even
an orange in the hands of a sick baby is likely to be taken from it, and the floral tributes on the casket of a citizen who has died abroad, and is being taken home for interment, are ruthlessly confiscated and destroyed. Of course occurrences like these do not tend to make the horticultural quarantine officials popular; but California has suffered too much from pests that came in accidentally and unnoticed to run any avoidable risks.
Horticultural regulations in the various counties are equally strict. Each county has a horticultural board, composed of three members. This board appoints local inspectors to any number that conditions appear to require; and has authority to order an inspection of any orchard, nursery, trees, plants, vegetables, fruit, packing house, storehouse, salesroom, or any other place or article that may be suspected of being affected with injurious insects, and to take steps to abate any pest found. It is required that all orchards be inspected at least once a year; that all horticultural inspectors shall be versed in entomology, and that they be instructed in the duties of their office by a competent teacher. As Superintendent Carnes, of the State Insectary, was conceded by all to be best fitted by temperament and attainments for such a task, he was detached from the Insectary many months ago, by appointment of Governor Gillette, to membership on the Board of Horticultural Examiners. This made it necessary for him to devote his time exclusively to the preparation of an extended series of questions for each county, and to conduct a separate examination in each county, of candidates for the position of horticultural inspectors. During his absence the responsible head of the State Insectary is Frederick Maskew, Acting Superintendent, to whose courtesy the writer is largely indebted for material used in the preparation of this article.
Mr. James Lick, of San Jose, California, was a plant lover, and introduced. many foreign plants, shrubs and trees for the ornamentation of his grounds. In the early seventies, the pest that became known as the San Jose scale, appeared on trees belonging to him, rapidly spreading to other orchards in the neighborhood, and later to all deciduous fruit
regions on the Pacific Coast, proving most injurious to pear, apple and peach trees. In 1893, it made its appearance near Charlottesville, Virginia, and investigation showed that Eastern nurserymen had scattered it broadcast over the Eastern and Southern States, through the sale of plum trees obtained in the San Jose district.
Before investigation was begun to determine from what country the San Jose scale had been introduced, Mr. Lick died. It being impossible to ascertain whence he had secured his plants, extensive explorations were made by Mr. Marlatt, of the Department of Agriculture, in order to find the natural habitat of the pest, as it was anticipated that its natural check would be discovered there also. Its true home was at last found, in the neighborhood of Pekin and Tientsin, China, where its enemy was discovered in the Asiatic ladybird-Chilocorus similis. A number of these ladybirds were imported, and the species has been bred to a considerable extent for the purpose
of checking, if possible, the pest in the Eastern United States.
However, in California a native parasitic insect, the Aphelinus fuscipennis, adapted its taste to the San Jose scale; and, finding the food supply so abundant, increased with extraordinary rapidity, so that it has brought the dreaded pest well under control. It still breaks out from time to time in unexpected places, but the shipment of a few colonies of its parasitic foe from the Insectary suffices to check it before it becomes a menace, so that it is no longer feared. This is one of the rather rare instances in which a native beneficial insect has adapted its taste to an imported pest.
Among other once serious pests that are now completely controlled by insect checks may be mentioned the soft brown scale on citrus fruits and the brown scale of the apricot, of which the natural checks are the two internal parasites, Encyrtus flavus and Comys fusca. In May of the present year, Mr. Maskew collected in the breeding cages of the Insectary, and shipped to endangered orchards, an average of no less than 12,000 flies of the last named species daily for a considerable period. The black scale that once appeared to threaten the very existence of the olive orchards, and that constituted a serious pest on citrus and many varieties of deciduous fruit trees, is fairly well controlled by an Australian ladybird, and a small internal parasite introduced through Charles P. Lounsbury, from South Africa.
It may be inferred that to import live beneficial insects from China, Australia or other remote countries is sometimes a matter of no small difficulty. Sometimes it is necessary to pot small trees infested with a scale pest, box them carefully, and ship them to the distant country in which the enemy of the pest is found. There they are unpacked and exposed to the action of the
eggs in those of the scales. Then the trees are boxed up again, conveyed to the seacoast, shipped across the ocean in cold storage, and taken to the State Insectary. There the trees are unboxed and placed in a breeding room, where development is rapid, owing to favorable conditions of light, heat and ventilation. In this manner the parasite of the purple scale on citrus fruit trees was introduced from the interior of China.
One of the first points for determination at the Insectary, when a new beneficial insect is received from abroad, is whether or not it is affected by a secondary parasite. That every form of life has its natural check is just as true of beneficial insects as it is of pests, so that, while there is little poetry, there is a great deal of truth in the screed: "Big fleas have little fleas
Upon their backs to bite 'em;
And so ad infinitum."
It is evident that if a secondary parasite were introduced along with the beneficial insect, to prey upon it and limit is increase, the very object in view in its introduction would be defeated. The breeding of insects in any quantities desired is a much less difficult undertaking than might be supposed. It is mainly a question of food supply, temperature, light and ventilation.
"It is a conservative estimate," said Mr. Maskew recently, "that one half of all the children now in California will some day be fruit growers, or the wives of fruit growers. If some of these can be given a fair idea of what we are trying to accomplish here, of the means necessary to the accomplishment of our ends, and of the importance of the work we are trying to do, to the agricultural
and horticultural interests of the State, there will be fewer obstacles in the way of the parasitologists who come after us." So, perhaps, not the least important work of the Insectary