The pine sawfly, Neodiprion sertifer, was first noted near Somerville in 1925. By 1943, it could be found practically over the entire northern half of the state. Red pine and Scotch pine are its favorite food plants and these are species that have been planted extensively for reforestation and soil conservation purposes.
In 1939, the Forest Insect Laboratory of the United States Department of Agriculture at New Haven, Conn., supplied parasites of the sawfly for release in New Jersey, and in 1940 it furnished breeding stock of two parasites to the Division's parasite laboratory at White Horse. One of these, Microplectron fuscipennis, which attacks the sawfly cocoons was comparatively easy to rear, and for the next five years the species was bred extensively and over twelve million individuals were released in more than 150 plantings involving nearly eight thousand acres.
The results of these liberations were varied, but nothing like control was obtained. In plantings that had been defoliated year after year, the litter was so deep and solidly matted that the parasites could not penetrate to the cocoons.
In view of the limitations of the parasite, an airplane-spraying service was made available in 1946–1947 to pine owners of ten or more acres for the application of a DDT solution. All arrangements were handled by Harold B. Girth, who contacted property owners, supplied air maps, picked out airports, etc., and checked results. On 53 properties 2,542 acres were sprayed, with good control of the sawfly.