Studies of the housefly, made by C. H. Richardson from 1914 to 1916, showed that early in the season the fly populations in towns, villages, and farms consist of a variety of kinds of flies, but by mid-summer the outstanding species is the common housefly (Musca domestica). He also showed that fly populations can be greatly reduced by elimination of breeding materials, principally accumulations of manure. Iron sulfate and carbon bisulfide proved effective in killing maggots in horse manure but some flies remained in spite of great care in removal of breeding places. In 1917 Alvah Peterson conducted an anti-fly campaign in the borough of Beach Haven, using a bait of molasses and sodium arsenate to supplement disposal of breeding materials. At a later date sprays were developed, particularly for treatment of dairy barns and use on animals.
In 1946, by legislative action, a new project was instituted to study biting flies in resort areas of the state and other insects affecting man and animals, Studies were initiated by John N. Belkin, but on his resignation a few months later Elton J. Hansens was assigned to the project.
By 1950 it was shown that the stable fly, a vicious biting pest in some shore areas, could be controlled by spraying DDT once every two weeks on vegetation which washed up on the shore of Barnegat Bay. An experimental control program was set up in cooperation with Seaside Park Borough by which it was shown that spraying to kill emerging flies greatly reduced fly annoyance on the beaches. Another biting fly, the salt marsh greenhead, is now under study. A detailed report of its life history and habits is not yet completed, but some promise of control by use of insecticides has come from applications against the larvae in salt marsh sod.
The reality of housefly resistance to DDT was vividly demonstrated by George W. Barber and John B. Schmitt when they found that concentrations of DDT that would kill ordinary houseflies in 15 minutes would not after two hours' exposure faze a strain of flies they had collected in a hotel kitchen. During the summer of 1948, resistant flies were collected from several dairy barns. Through the following months many tests were made on a large group of insecticides, and strains were developed in the laboratory which were highly resistant to DDT, methoxychlor, and other chlorinated hydrocarbon insecticides. After four years the fly population in treated barns was found to be resistant to all of these new insecticides and farmers had to revert to use of pyrethrum space sprays. At the same time, Barber was studying housefly behavior under a grant from the Quartermaster Corps, U.S. Army. Today, with emphasis in housefly control changing to use of baits of various kinds, his precise and detailed work takes on added significance. In 1952, however, Diazinon, a new residual phosphate insecticide, was reported as effective against resistant houseflies, and John Hadjinicolaou, a Mundt-Fulbright scholar from Athens, Greece, showed in field tests that dieldrin and other insecticides applied against housefly larvae resulted in the production of highly resistant strains of larvae and adult flies within a single season.
In 1947, studies of control of poultry pests showed that lindane, when applied as a roost paint, gave excellent and lasting control of poultry lice and light infestations of common poultry mites, although heavy mite infestations necessitated applications to both roost and nesting areas. Lindane was also found effective when applied to birds infested with feather mite.
In 1951, studies on the parasites of all New Jersey mammals were instituted. With the cooperation of the New Jersey State Department of Agriculture and other agencies, during the following two years nearly three thousand rats were deparasitized. The study was then broadened to include many other mammals, collected for the most part by personnel of the Fish and Game Division of the New Jersey Department of Conservation and Economic Development, and the New Jersey Department of Agriculture. The identification of the parasites is a laborious procedure but with the help of graduate students, the identification of these fleas, lice, ticks, and mites is progressing.