burgess: gypsy moth and barrier zone 
53 
difficulty. This is not a hypothetical case, for Norway spruces have 
been observed which were struggling against the combined infestation 
of the two insects and a poor site, much to their detriment. The pres¬ 
ence of the sawfly emphasizes the care necessary to maintain ornamental 
spruces in a state of good health. 
REFERENCES 
Balch, R. E. 1936:—“The European spruce sawfly outbreak in 1935.” Canadian 
Entomologist 68:23-31. 
MacAloney, H. J. 1936:—“The European spruce sawfly.” Tree Pest Leaflet No. 6. 
Mass. Forest and Park Association. 
Peirson, H. B. 1936:—“The European spruce sawfly.” Maine Forest Service Circ. 3. 
Friend, R. B. and Plumb, G. H. 1938:—“The control of the European pine shoot 
moth.” Journal of Economic Entomology 31:176-183. 
THE GYPSY MOTH AS IT APPROACHES THE BARRIER 
ZONE 
By A. F. Burgess, United States Bureau of Entomology and Plant Quarantine , 
Greenfield , Massachusetts 
In 1923 an area which is known as the barrier zone was selected in 
territory between the Canadian border and Long Island Sound east of 
the Hudson River and covering a similar area adjoining it in Vermont, 
Massachusetts, and Connecticut. The purpose of the selection of this 
area was to give it periodical inspections and clean up colonies of the in¬ 
sect that might be established in it, so as to prevent westward spread 
of the pest to adjoining and distant states. Most of the work in New 
York state has been done by the Department of Conservation in coopera¬ 
tion with the Bureau of Entomology and Plant Quarantine. 
Since that work began many colonies have been found and extermi¬ 
nated which were scattered throughout the zone, millions of acres of 
tree growth including forests have been examined one or more times. 
As a result of the intensive methods that have been employed in clean¬ 
ing up infestations, territory in New York state aggregating 511,000 
acres on the western border of the zone has been eliminated from further 
inspection, and additional territory on the east side of the zone in the 
northern part of Vermont aggregating 686,000 acres together with two 
smaller areas contiguous to the zone in Connecticut covering 102,900 
acres, have been added to the zone. Based on the work that was fin¬ 
ished during the past year towns along the western border of the present 
zone in New York aggregating 521,000 acres, together with towns simi- 
