• Struble, David
  Maine Department of Conservation, Bureau of Forestry, Division of Entomology
  
• Trial, Henry Jr.
  Maine Department of Conservation, Bureau of Forestry, Division of Entomology
  
• Stark, Douglas (ed)
  Maine Department of Conservation, Bureau of Forestry, Division of Entomology
  

In 1975 the Maine Forest Service conducted a 2,233,500 acre areal spray project against the spruce budworm in northern and eastern Maine. The goal of the operation was to reduce budworm defoliation and thus prevent substantial mortality in areas of high budworm hazard. The chemicals used were Zectran, Sevin-4-Oil, and Sumithion. Total cost of the project was 6.2 million dollars.

Extreme larval populations and accelerated larval development resulted in increased pre-spray bud damage which decreased the treatment potential for foliage protection.

For the following operational chemicals, Sevin-4-Oil, Sumithion, and Zectran, the respective percentages of mean foliage protection were 37.7, 25.6, 39.9; the respective percentages of mean larval reduction were 90.4, 90.7, 98.1 and the respective mean number of survivors per 18-inch tip were 11.7, 13.1, 2.1. The average budworm larval-pupal parasitism was approximately 21%. Light trap survey data did not indicated any widespread moth flights. The average density of  egg masses in and adjacent to the 1974 spray area was significantly lower that the 1974 levels. Within treated areas egg mass density was less that adjacent unsprayed areas.

Cooperative research and monitoring projects conducted by the U.S. Forest Service, the U.S. Fish and Wildlife Service, the University of Maine, Lake Ontario Environmental Laboratory and Maine Bureau of Forestry are listed.

Hazard ratings based on egg mass and tree condition surveys in conjunction with the aerial damage survey indicate 3.5 million acres of spruce and fir are in critical condition. Lacking reduction in projected larval populations, substantial mortality of spruce and fir should occur in these critical areas. Projections for tree damage in adjacent Canadian providences and the State of New Hampshire are included.