The program of mosquito control in New Jersey has always emphasized the necessity of removal of breeding places. And fundamental to all control activities has been the need for knowledge of kinds and numbers of mosquitoes. Although the basic studies in mosquito biology were made by Smith and his associates at the turn of the century, during the last twenty-five years important and various studies of habits, life histories, and associations have been made.
Before 1912 anti-mosquito work had been conducted mainly by the state through the Agricultural Experiment Station with the cooperation of local boards of health, but the passage of the county mosquito commission law in 1912, put control work under the county mosquito extermination commissions. When in 1912 Headlee succeeded Smith as Station entomologist, he directed attention to scientific study of the life habits and control of the insects, and under his supervision, from 1912 to 1944 the control program advanced steadily in matters of legislation, organization, and engineering techniques.
National and international authorities in the field gather once a year at meetings of the New Jersey Mosquito Extermination Association founded in 1914. To give technical workers opportunity for frequent conferences, the Associated Executives in Mosquito Control was formed in 1921. At their monthly meetings these technical workers discuss and report developments and new ideas. The printed Proceedings of the Mosquito Extermination Association have worldwide circulation. In 1945 the Rutgers University Press published Headlee's The Mosquitoes of New Jersey and Their Control. In 1946, a number of popular bulletins including The Story of the Mosquito were published.
Under Headlee's administration, it was established that practically all parts of the salt marsh were capable of producing mosquitoes. Cooperative studies with F. E. Chidester resulted in a better understanding of the influence of the salinity of water on the development of certain species of mosquito larvae, and Chidester's own study threw more light on the principle fish enemies of salt-marsh mosquitoes. The work of Willem Rudolfs, biochemist in entomology, on odors which attract or repel these insects aided the development of traps by which the prevalence of mosquitoes in different localities could be detected. Rudolfs also made extensive observations on the relations between atmospheric conditions and mosquito behavior.
Development of a trap device to measure mosquito abundance was started by Headlee in 1930. Failure with the first traps devised was followed by the development in 1931 of a successful horizontal trap which used light as an attractant. The vertical trap which succeeded it a year later continues to be used by the mosquito commissions in checking effectiveness of local control, and by the Department of Entomology in evaluating control programs. By means of these traps, the department is able to check numbers of mosquitoes from season to season and between areas.
The availability of PWA and CCC workers from agencies created by the government to relieve the economic depression of the early thirties, resulted in thousands of feet of ditches being cut by hand. Although here and there the early machines, developed for cutting new ditches and cleaning old ones, have continued in use, their weight and inability to operate in some areas made them on the whole unsatisfactory. Several good machines were developed by Fred Reiley, but it was not until after World War II that a light-weight machine suitable for mosquito-control use was developed by commercial manufacturers. The scavel, developed in Connecticut, also proved to be a most useful tool for ditch clearing and cutting on New Jersey salt marshes.
Among important advances in chemical control of mosquitoes was the development in 1933 of a set of specifications for oils most efficient for this purpose, and of a pyrethrum-oil larvicide formulation (popularly known as New Jersey Mosquito Larvicide), which was later found to be also an effective area repellent and thus useful in protecting outdoor gatherings from mosquito annoyance.
Tests in New Jersey were among the first to show that a single application of DDT made to the walls and ceiling of a building would control Anopheles quadrimaculatus adults for several months. Cooperative studies with the Morris County Mosquito Commission in 1946 showed that DDT could be used also as a preflood treatment for fresh-water swamp mosquitoes. It was also demonstrated that light dosages of DDT in oil with a spreader could replace fuel oil in larval control. When applied from a small dispenser, this formulation was shown to reduce by as much as 90 per cent the cost of labor and materials used for treating local breeding areas. As a result of further study in 1947 and 1948 by Stanley D. Carpenter and Daniel M. Jobbins, various spreaders were suggested for use on polluted and brackish water. Mosquito control agencies have since made wide use of small dispensers for application of these improved formulations of toxicant plus spreader. It is interesting to note that it was the extensive studies on spreaders conducted in the department by Joseph M. Ginsburg in the early 30's which led to this development more than fifteen years later.
With the advent of DDT, studies were made of its toxicity to mosquito larvae and to fish both in the laboratory and in the field. More recently a number of the newer toxicants were tested. Among the many new spreading agents which have been under study some are also highly toxic to mosquito pupae.
In 1944 some of the earliest observations on the use of fog machines for control of adult mosquitoes were made. Later, when the uses and limitations of these machines were worked out in cooperative studies with several mosquito commissions, it was found that fog machines could be used effectively; as a result many control agencies now make regular use of fogging equipment.
The prosecution of two world wars have imposed special conditions which have enlisted the help of those working on mosquito control. In World War I Headlee's advice was sought in the organization of mosquito-control methods in the vicinity of the shipyards in New Jersey, at Wilmington, N. C., and at Hog Island. During World War 11 the problem of malaria, especially as it concerned the introduction of the disease by returning servicemen, became particularly important. Transmitted in New Jersey by one mosquito species (Anopheles quadrimaculatus), a system was set up for immediate surveys and control of all Anopheles within the radius of a mile of the residence of any reported malaria victim. Though hundreds of malaria cases were reported in the state, there was no wartime malaria outbreak.
In 1949 Boards of Freeholders were given the power to appoint county Extermination commissions, but with this exception state laws have undergone little change since the system of county commissions was established in 1912. Plans of work and budgets of the commissions are subject to the approval of the Director of the New Jersey Agricultural Experiment Station. By 1945 there were fifteen commissions which supervise mosquito control activities in all important breeding areas in the state, except along the Delaware River and Bay, at a current annual state expenditure Of 1.25 million.
An appropriation of fifty thousand dollars for air spraying four seashore counties became available in 1949 by the enactment of the Frazer and Smith bill. During 1949 this program was under the administrative control of the N. J. Department of Health. Subsequently that part of Burlington County bordering tidal water was included in the area to be sprayed, and administration of the aircraft spraying work became a part of the Experiment Station program.
In the years immediately following World War II, mosquito control agencies emphasized the use of DDT and other chemicals, but in 1954 the trend was back toward the use of a combination of permanent control measures and the more temporarily effective insecticides. Postwar urbanization and industrial development has brought increasing demands for drainage work. Today the public demands a degree of mosquito control undreamed of at the turn of the century.
In 1944, Bailey B. Pepper succeeded Headlee in the direction of mosquito investigations. From 1928 until his death in 1932, Frank Miller was particularly concerned with control agency contacts and research, assisted by Thomas D. Mulhern and, from 1934 to 1938, by Daniel M. Jobbins. Mulhern carried on much of tile work from Miller's death until 1948-1949, when Mulhern resigned and Jobbins returned to the department to take direct charge of the project. Insecticide investigations have been conducted by Joseph N. Ginsburg since 1925. In addition studies of mosquito biology and control were made by Elton J. Hansens (1944-1946), Stanley D. Carpenter (1947), and Lyle E. Hagmann (1948 to date).