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Image provided by: University of California, Riverside; Riverside, CA
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CALIFORNIA'S SANEST BUG HOUSE The State Insectary Leads the World in the Propagation and Dis tribution of insects That Devour Insects That Devnurthe Crops John L. Cowan ONE of the newest of applied sciences Is parasitology. In Cali fornia this has been developed to a greater extent than elsewhere for the conserving of the great fruit and vegetable producing- industries for which the state is famous. Freed from eclentific verbiage, the essence of the new science as applied -to agriculture and horticulture is to put bugs to fight ing bugs, or. in other words, to combat Insect pests by Introducing their nat ural enemies. By far the most Important establish ment In the world devoted to the en couragement of parasitology Is the California state insectary. located in the capitol grounds at Sacramento. Here millions of predaceous insects (notably the ladybird beetles, collected In the . \u25a0winter month from the hlg-h Sierras) are kept In cold storage until needed In the melon fields and apple and peach orchards, and millions 'jof minute para eltes are bred In confinement, for dis tribution wherever agricultural or hor ticultural pests make their appearance •within the confines of the state. Tt Is now regarded by scientists as an established fact that every form of life has one or more natural checks that limit Its increase In numbers. Birds constitute one of the most Important checks upon the multiplication of insect •' life, but it appears that every Insect epecies that feeds upon vegetable tis eues has insect foes that feed upon it. \Ter« It not for^these natural checks •upon Insects that devour vegetation their powers of reproduction are such that they would soon consume every fTf^n thing. PometimPß the insect checks upon j-ests are predaceous in their habits: t*iat Is to say. they pounce upon the ptpt insects and devour them. Of this nature are • the ladybird beetles, of which there are upward of 2,000 spe cies, which are the enemies of all va rieties of plant lice and seal© Insects. Sometimes thoy are parasitic — that Is ' to say, they deposit their eggs In the grub of the pest, end as the young hatch and develop they feed upon the \u25a0urroundirg tissues, and the victim (known as the "host") Is killed long before it reaches maturity. Strictly speaking, the science of parasitology has to do with the first named class only. But, es a matter of fact, para fitolosiEts concern, themselves with any insects that destroy other Insects that are injurious, whether predaceous or parasitic. , In most regions Insect pests are com bated by means, of poisonous Bprays, dips, washes, powder and gases; or by hand picking; or even by digging trees or plants out root and all and burning them. Even in California these meth ods arc used extensively. The chief, objections to them are that they are clumsy, expensive. Inefficient and of* only temporary effect. It Is claimed thnt they have never yet resulted In the extermination or permanent sub jection of a single Insect pest. The "orchard or truck garden that has been treated with insecticides this year must be similarly treated next year, and every year In the future. The parasitologist contends that mis recurring annual expense Is unneces earv. His remedy Is to search the •world for the natural foe of the pest and put It to work fighting th« farm er's ar.^ fruit grower's battles. In the absence of either natural or artificial * checks, the only limitation to the mul tiplication of the pest is Its food sup ply — that Is, the tree or plant upon which it feeds. Similarly the only limitation to the multiplication of the numbers of a beneficial Insect Is its food supply — the pest upon - which It feeds. Consequently, the more numer ous and destructive \he pest, the more rapidly will its check multiply once the parasitologists have succeeded in in troducing !u , In every life zone nature has estab lished a balance between vegetable life, insect pest and parasitic or predaceous locs. As long as this balance Is un disturbed the Insects that are capable of becoming pests (and this includes all that feed upon vegetable tissues) do no appreciable damage, owing to the activity of their natural checks. But man disturbs the life equilibrium in various ways. By Irrigation and cultivation' he brings vegetation for ward in. certain regions at a season of the year when ' desert conditions were natural. With an abundant food sup i>ly thus provided, plant lice . thrive at a period when their natural checks are dormant. This is the reason why the melon aphis gained such a foothold in the Imperial valley of California that the extinction of the great industry of 'growing melons, • cantaloupes and cu cumbers for early, shipment to the east ern markets seemed imminent. The condition was met by the para sitologists of the state Insectary* Last winter- they sent field agents to the canyons of the high Sierras, where they collected 1,707 pounds of lady birds, or approximately 43,000,000. These were placed in cold storage in the insectary. Then when- the melon aphis made its accustomed appearance in the Imperial valley in April the lady birds were shipped for liberation In the melon fields. In April more than ; 11, 000,000 ladVblrds wtre- shipped from the insectary to the Imperial valley and millions mori in May, saving, the melon crop, worth at least $500,000.- Later in the season many millions". of ladybirds were shipped to sections of •the state in which aphid pests ap peared on apple Vand peach trees. Another way In which the natural balance among all forms of life is dis turbed is by the extermination of in sectivorous birds. That tfiis has been an- important factor in contributing to the growing seriousness of rav ages the whole country over can not be questioned. But the disturbance of the ' natural : life equilibrium o with which parasitologists are most- concerned is that due to the importation of foreign * Insects. Practically all serious ' pests that worry the farmer, gardener and fruit grower (such* as the "cotton boll weevil, the San* Joee scale, tho gipsy moth, the coupling, moth and hundreds "of others) have been brought to America from foreign countries. Usually these "foreign pests are brought to America unnoticed. A for eign tree, shrub or flower is Imported, and it is very likely that the almost microscopic eggs of /some insect are present on it, The plant takes root and grows and the Insect egg's hatch. Years may pass "before the Imported Insect; in its new environment, becomes sufficiently numerous to ; constitute a menace to the form of vegetation upon which it flourishes. : Then it is recog-^ •'' nized 'as a \u25a0 pest and poisonous, gases," yowders. sprays and other mechanl cat : methods 6T 'control '\u25a0' are tried. In its natural home that particular insect probably did very little damage, because it was held In check byj: Its natural , enemy, in the absence of _ its natural enemy its numbers "increase with the amazing Vapidity character istic ; of insect life, when an abundant food supply is found,;so;that it devours all before it, often threatening the very existence. of important agricultural and horticultural industries. 7 r ,/• • In emergencies of this;, kind, all known mechanical methods of contro are resorted to, but permanent rellet . comes only through the introduction of the same Insect foea of the pest that held it in check in its natural habitat Recognizing this fact, Californ!a.has an explorer in the field, ransacking the remotest corners. of the earth In search of beneficial Insects. Thlsis George Compere, employed Jointly by the hor ticultural commission of California and the entomological bureau of West Aus tralia, for no other purpose than to search the world for the Insect ene mies of agricultural pests. Similar work Is clone by the field agents of the federal bureau of entomology, through whose agency some of the most impor tant beneficial Insects „ have been , in troduced; However, California has sys tematized this work to a greater extent than any other state or country, and breeds beneficial Insects for distribu tion to farmers and orchardists on a larger scale than has ever before been attempted.V ; , : \u25a0 -" . "/'. /The breeding'of beneficial Insects. in captivity to any, extent desired is sim ply "a question of providing an abundant supply/ of the appropriate; food -at the fight time/ with the proper conditions of light, heat and ventilation- for -Insect development. The insectary consists of a:large : number.of ] glass -walled { rooms, arranged around a central "court.;, .Each room is heated 'and' ventilated : inde pendently; of all the others, and' so ar ranged that the air can be pumped out and fresh air supplied from the- base ment, at any temperature desired. It Is, therefore, possible to regulate the temperature to the fraction of a de gree. The only food upon which para sites flourish is the pest that nature designed them to hold in check. It Is. therefore, necessary to keep an abund ance of pest infested leaves, twigs and fruit on hand, In order that the bene ficial Insects may have a plentiful food supply. ?-. .'.'• Most Insects, whether beneficial or Injurious, may be kept In a dormant condition, of practically suspended ani mation, by simply keeping them In a room with a temperature too low to promote development. In this way, breeding operations at the California state Insectary are reduced to the low est possible* terms. . "When a pest Is Inactive/ its parasitic foes at the/ in sectary are kept In a dormant condi tion. The moment . notice .Is received that a particular pest has broken out In" any. part of the state the parasites of that pest are taken to an apartment where Ithe proper, conditions of heat, light and ventilation may be supplied, and an abundance of their appropriate food is furnished. Almost instantly the dormant insects begin to awaken to activity:- soon, the females begin to deposit their^ eggs, and, in a very few days the parasit" in^sts of the Insect The San Francisco Sunday cau ary are ready to make shipments of thousands of insects. These are dis tributed free to any part of the state in which their services may be needed, and the express company delivers pack ages containing them and returns the shipping cases when empty, free of cost within, the limits of the state. Breeding usually is carried on in breeding cages, made by covering * light wooden frame with, insect net ting. "When the .matured insects issue they al(ght on the walls of the cages. The parasitologist then opens the door of the cage and quickly places a wide necked vial over the tiny insect. In stinctively the insect flies back into th 9 vial and the operator repeats the proc ess again and again until he has as many in the vial a3 he desires. Usually about t% parasites constitute a "col ony." but much larger colonies are often shipped. That the parasitologists of the stat-J insectary have "made good" Is not open to question, as any one familfar with the work of the institution well knows. Among the pests that have been com pletely subdued, one of the moat de structive was the cottony cushion scale. A little more than 20 years ago this threatened the every existence of the orange growing industry, shipments of oranges falling from 8,000 carloads in one year to 600 the next. It was brought under subjection by predaceous *nd parasitic foes introduced from Australia, the country of Its origin Similarly the black scale that threat ened the- ruin of the olive orchards and spread to nearly all deciduous fruits la controlled .by a little ladybird (rhi robiua ventralls) and a small internal parasite (scutellista cyanea). The San Jose scale has spread from ocean to ocean and ha 3 led to jnore legislation on the part of the various states and foreign countries than all other insect pests combined. It is no longer a dangerous pest in California.- because wherever it appears the parasitologists of the state Insectary ship colonies of Its natural enemies, which quickly cause Its disappearance. Several varie ties of ladybird beetles prey upon it. materially lessening its numbers, but its most Inveterate foe Is a minute hymenopterou3 parasite known as the aphelinus fuscipennis. Other once dan gerous pests that have been completely subjugated In the same manner are the soft brown scale, the brown apricot scale, the yellow scale and pulvinaria lnnumerabilis. Many other pests are partially controlled by Insect enemies bred at the stato insectary, and tha scientists In charge feel sure that time labor and patience will enable them to completely control every insect pest that vexes the farmer and fruit grower They accept It as axiomatic that nature never makes a mistake, that for every form of life there is a natural check to prevent It from becoming redundant J To find that natural check. lntroduc-J it where needed and giv© It a chanc/ to perform Its mission Is the essencd of tha scienc* ox naxasitolosy. ~