Search

On the basis of field studies and experiments, under conditions where codling moth, Carpocapsa pomonella Linn., normally infests 100% of all the fruit borne by unsprayed trees, it has been found that codling moth infestation, under arsenical treatments, varies, within limits, inversely as the amount of lead arsenate per tree per treatment, inversely as the maintenance of coating during the periods of entry by larvae of the first and of the second broods, inversely as the combined factors of lead arsenate and maintenance, and directly as the concentration of infestation.

The broad outlines of codling moth control were set forth by Mark V. Slingerland thirty-three years ago. Since that time the primary improvement has occurred in the development of control through the use of stomach poison insecticides and the secondary in the use of scraping and the development of lethal bands. The efficiency of stomach poison insecticidal applications varies inversely as the density of the codling moth population. With annual crops of apples, temperature favorable to the production of many broods, weather favorable to heavy oviposition activities, and inadequate practice of known measures of control, such dense populations of codling moth can be built up that the practice of no one or all of the ordinary measures of control will serve to secure good commercially clean crops. Some new method of administering cheaply and promptly a knock-out blow to the codling moth should be sought. The only time when all individuals of the codling moth are in the same stage for a considerable period of time is during the period of hibernation. It is probable that this is the most promising point of artificial attack. Pine oils have shown considerable promise for this purpose and have produced some marked reductions in the density of codling moth populations. Other agencies, such as gas and heat, should be tried.

This paper reviews the results of a three year cooperative effort against the codling moth, Carpocapsa pomonella, in a heavily infested district near Glassboro, New Jersey. This cooperation existed between a group of more than twelve growers, whose properties involved a total of over 1400 acres of bearing apple, and the New Jersey Agricultural Experiment Station. In 1925, which is the year previous to the inception of this effort, the average percentage of fruit free from codling moth at picking time was 47.4. In 1926 the average clean fruit at picking time in a crop of 280, 200 bushels was 68.8%. In 1927 the average clean fruit at picking time in a crop of 378, 554 bushels was 80.8%. In 1928 the average clean fruit in a crop of 309, 499 bushels was 81.1%. Of course there were individuals, and large producers too, that reached more than 95% clean fruit but there were others that were not as successful and the average consequently stood at the point mentioned. The small increase in average clean fruit at picking time in 1928 may be attributed mainly to the fear of arsenical residue.

Legal relationship comes into existence between Federal and State quarantine officers when an interstate plant quarantine, having intrastate features, is put into force within the United States. Practical relationships between Federal and State quarantine officers may rise from sources such as state instituted quarantines imposing restrictions that bear incidentally upon interstate commerce, and international quarantines which bear onerously upon some section or sections of the United States. To make these relationships efficient it is necessary that the Federal and State quarantine officers should make their plans and pursue their duties in a spirit of cooperation and mutual helpfulness. In view of the fact that nearly all plant quarantines interfere somewhere, somehow with private rights and may constitute an interference with the legitimate business of large groups of our citizens, it is obvious that in addition to insect and plant disease distribution facts, the effect of such quarantine action upon the legitimate business, bound to be effected by it, must be considered as an important factor in determining when, where and how quarantine lines shall be laid. Quarantines must not only be laid with judgment and extreme care but they must be enforced with sympathetic consideration for the interests of those citizens whose legitimate business is being injured thereby and not in the spirit of the blood hound of the law engaged solely in the process of catching the evil doer. The national plant board is designed to represent the interests of the regional plant boards where these interests are national in scope and serves in matters of this kind as a medium through which to present to the Federal Plant Quarantine and Control Administration the combined views of the state authorities. Naturally also the national plant board must think along national lines and afford leadership to the regional plant boards.

Soil and soil-water heating is likely to prove a limiting factor in the use of electromagnetic waves against soil infesting insects. Irradiation of foliage wall of the apple tree with ordinary white light in the amount of ten foot candles reduced fruit infestation by first brood codling moth 50%. Eggs are, however, frequently deposited in this intensity. Irradiation in the neighborhood of thirty foot candles seems likely to be required to prevent free oviposition. The violet end of the spectrum excites the moth to apparently normal oviposition. The red end tends to produce abnormal activity with some egg laying.

The large expenditures for control of gipsy moth, Porthetriadispar , have rapidly reduced the infestation, the Federal Government working in co-operation with the State of New Jersey. It is held that extermination is worth the cost, especially if a barrier zone be established in New York State.

Through a period of three years, 1928, 1929 and 1930, the thermal constant has been used for practical determination of the time when cover spraying should start for the first and for the second broods of codling moth and has seemed to be eminently successful for that purpose. It seems likely that the thermal constant can be used as a satisfactory practical determinator of the length of periods during which spray coatings must be maintained on fruit and foliage against entry by larvae of the first and of the second broods. When the average weekly minimum temperatures reach about 60o F pupation of summer larvae seems to cease and it is thought that these minimum temperatures are probably the agency limiting the number of codling moth broods.

To meet his problems the economic entomologist must he looking- ever more deeply into the nature of insect life and its reaction to the physical and biological environment in which it is found. His sweep of basic information must involve a working knowledge of the principles of physics, chemistry, biology and entomology. He must not neglect any phase of entomology as being unimportant for his purposes. His organization for research must involve the physical, chemical, biological points of view as well as the taxonomic, structural, developmental and physiological standpoints of his specialty. The fields of chemical control is now coming into its own. The field of biological control is just opening up as is also the field of physical control. The opportunities for accomplishment in public service through economic entomological endeavor never were greater but the difficulty of the problems involved is constantly increasing and demanding greater and greater keenness.

Pioneer work in economic entomology consisted in the determination of the insect’s life history and habits without more than casual regard to the environment in which it lived. From time to time, however, various workers have called attention to the fatal effects of the extremes of temperature and moisture, and a few persons have pursued systematic inquiry into the relations existing between temperature and insect life. Others have used various arthropods in determining the response of protoplasm to various stimuli. The last two types of investigation have proceeded far enough to show that insects in common with other organisms have minimum, optimum and maximum relations to each important stimulus to which they are subjected. More than enough work has been done to show that the life economy of the insect depends to a very large extent directly and indirectly upon the physical, chemical, and animate environment in which it lives, and that no fundamental understanding of its life economy can be reached until the effect of its environment is understood.

Continuance of the organized efforts of growers against the codling moth, Carpocapsa pomonella , in the Glassboro district has resulted in a further material increase in fruit free from injury by that insect. In 1925 the growers who form this organization picked 50% of their total fruit free from codling moth injury, in 1926 they picked 68.8% free, and in 1927 they picked 82.1% free. The timing, composition and methods of applying insecticide materials are the dominant factors in obtaining this result but orchard sanitation measures, such as proper disposal of used baskets, scraping rough-barked trees, and the use of burlap bands, play a minor but important part in obtaining this result.

All larvae of Bembecia marginata pupate in latter part of summer. Work on both raspberry and blackberry seems to be of a crown-boring nature. Tobacco dust, properly used, destroys all larvae and leaves plants apparently unhurt. Margin of safety is much wider in tobacco dust treatments.

A mixture of pyrethrum extract and soap can be used to destroy wireworms without injuring the plants on which they are feeding. Soils through which this mixture penetrates affect the toxicity of both the pyrethrum extract and the soap. This reduction in toxicity is least when the soil is composed exclusively of sand and increases as the clay component becomes larger.

At the outset the writers wish to state the present status of mosquito work in New Jersey. Approximately 95,000 acres of the salt marsh has been rendered reasonably free from mosquito breeding. This has involved the cutting of about 11½ million feet of ditches 10 inches wide and thirty inches deep or their equivalent, the building of 17.2 miles of dike, the installation of 76 sluices and tide gates (representing 842 sq. ft. of cross section outlet opening), the installation of one four and one twelve inch centrifugal pump and the connection of 100 acres of marsh with a large sewage pumping plant. Approximately 50 per cent of the reasonably permanent fresh water mosquito breeding pools scattered over 315,000 acres of upland has been permanently eliminated.

Common white edible beans are protected from later attack by the common bean Weevil (Bruchus obtectus) when mixed in proper proportions With ground burned lime (CaO), hydrated lime Ca (OH)2 calcium chloride CaCl2, calcium sulfate CaSO4, dolomite, Highland Clay, Bond D Clay and Milltown Ball Clay No. 9. The protection which is afforded by these materials is most marked in the case of Milltown Ball Clay No. 9, and seems not to be connected with atmospheric moisture or chemical state of the dust materials. The protective ability of these materials appears to be correlated with the degree to which they exhibit a colloidal character-the more colloidal the more effective, the less collodial the less effective. This physical character seems to operate through preventing the larva of the bean weevil from obtaining sufficient foothold upon the surface of the bean seed to drill its way into the bean. Milltown Ball Clay No. 9, which is the most colloidal of all the dust materials worked with, appears to afford protection to wheat and shelled corn from later attack by the angoumois grain moth (Sitotroga cerealella) . This clay apparently also has an insect reducing power when not in direct contact with the immature stages of the insects themselves. This insect infestation reducing power appears both in the case of the bean weevil and the angoumois grain moth.

In the production of high temperature lethal effects on certain insects subjected to lines of force in an electrostatic field, it is a matter of prime importance that internal heat production shall be as rapid as possible. This speeding up of heat production can be accomplished through increasing the strength of the electrostatic field.

Electric energy propagated in an electro-static field at the rate of from 1,000,000 to 3,000,000 cycles per second with a field strength of 4,000 volts per inch can be used to destroy certain insects enclosed in the electro-static field without damage to their host plants. When, however, the electric energy is propagated at the rate of from 12,000,000 to 15,000,000 cycles per second with a field strength of 4,000 volts per inch both the insects and the plants are promptly destroyed. Thus there appears a differential in the effect of electro-magnetic waves on insects and their host plants and that frequency in their rate of propagation is apparently the primary selective factor.

This paper gives the results of one year's effort against the codling moth, Carpocapsa Pomonella, carried out by a group of eleven growers associated for that purpose and cooperating with the entomologist of the New Jersey Agricultural Experiment Station and shows: (1) that under codling moth infestation conditions, indicated by the fact that the late fruit in the check orchard averaged five injuries per apple, 73,850 bearing apple trees, covering 1,376 acres of orchard land, produced 280,200 bushels of fruit of which 192,320 bushels, or 68.8%, were absolutely free from all codling moth injury; (2) that this percentage of 68.S represents a 20.5% increase in fruit absolutely free from codling moth injury over the conditions obtaining the previous year; (3) that the maximum amount of fruit absolutely free from codling moth injury at picking time obtained on any one of these properties was 97%; (4) that the principal factors underlying this accomplishment were more timely and accurate spray applications and the more intelligent and careful use of orchard sanitation measures, such as scraping the rough bark from the tree, the utilization of burlap bands and the partial or complete elimination of the used containers as a source of codling moth infestation. The conclusions are: (1) that, under the local conditions of heavy infestation of codling moth, this insect can be suppressed by intensive work against it; (2) that the most intensive part of the effort is the cover spray program against the entering larvae of the first brood; (3) that, where the insect has been suppressed, a very high percentage of the picked fruit can be brought through absolutely free from codling moth injury by intensive work against the first brood only.

The eight hundred and fifty-five gipsy moth (Porthetria dispar Linn.) colonies in New Jersey in 1920-1921 were reduced to two hundred and sixteen in 1921-1922 and further reduced to ninety-eight in 1922-1923. Fifteen areas of slight infestation unconnected with the main area were apparently completely exterminated by the completion of the work in 1921-1922. Five hundred square miles of the original area of infestation has been reduced to about two hundred and fifty square miles. With the completion of the year 1922-1923 approximately d778,335.31 have been spent of which approximately one-half had been furnished by the state and private sources and one-half by the United States Department of Agriculture. Infested shipments of nursery stock have been received from New England as follows:—In 1921-1922 twelve; in 1922—1923 fourteen; 1923-1924 (report to December 12, 1923) two. Ultimate success in gipsy moth work in New Jersey means, not only the extermination of the present infestation but, the prevention of rein-festation from any source whatsoever and, consequently, New Jersey has a vital interest in the prevention of the spread of the gipsy moth from the great infested area in the New England states.