22 CIRCULAR 4 64, U. S. DEPARTMENT OF AGRICULTURE 



in many areas poplar, linden, willow, and, to a less extent, some of 

 the oaks have been used. In the rural sections there has been rela- 

 tively little roadside planting, and most of the shade trees are seedlings 

 or have developed from sprouts from trees that have previously been 

 cut. On private grounds there is a wide range of species, both native 

 and exotic, and on such properties there are frequently many trees 

 that are suspectible to gypsy moth attack. 



To obtain information as to the species that are growing on trunk- 

 line roads, in the summer of 1936 a hurried survey was made on one 

 of the principal State roads from the New York State line through 

 central Massachusetts, swinging southeast, and extending diagonally 

 through Barnstable County to Orleans on Cape Cod. The route 

 covered 260 miles of road, 48 miles of which was classified as city 

 and 212 as rural. The tree growth for 50 feet on each side of the 

 road was noted, because trees growing within these strips will even- 

 tually furnish shade for the highway. As a result of this survey 38.5 

 percent of the trees were rated as favored species, 27 percent were 

 conifers and beech, which are highly favored during certain stages of 

 the insect's development, 26.5 percent were far less favored but occa- 

 sionally defoliated, and 8 percent were in the unfavored group. 

 About 51 miles of this road was open country with no trees, and there 

 were additional areas where trees had been cut and were being replaced 

 by sprout growth. These sprout, or brush, areas were about 50 per- 

 cent favored food. The species growing in the wooded areas adjoin- 

 ing these strips along the highway, and in the forest areas that were 

 more remote, varied greatly in different localities, but it is estimated 

 that more than half the tree growth was of favored species. 



A survey of this type does not show what conditions exist in sec- 

 tions north or south of the road that was selected or on rural or unim- 

 proved roads. A larger percentage of favored food plants might be 

 expected southward toward Long Island Sound, and of less favored 

 ones in southern Vermont, New Hampshire, and Maine. The 

 information obtained, however, indicates the necessity of protecting 

 roadside trees from the gypsy moth. Officials in charge of tree pro- 

 tection could well afford to have maps indicating the growth along the 

 streets under their control as a basis for plamring for protection or 

 replacement of the most desirable species. An endeavor should be 

 made to remove as much of the favored growth as possible and to 

 encourage the growth of nonfavored trees. When it is impractical to 

 do this, treatment should be applied for the protection of the favored 

 species. Where solid woodland adjoining the road is heavily infested 

 with the gypsy moth, roadside trees will be denuded by migrating 

 caterpillars. In such cases protective work should be done to prevent 

 defoliation, and the methods that can be most economically employed 

 should be put into practice in an area adjoining the trees along the 

 roadway. The size of this area will depend upon the severity of the 

 infestation. 



THE WOODLAND PROBLEM 



In the barrier zone and the adjoining areas, as well as in isolated 

 infestations beyond the zone, intensive methods must be applied to 

 curtail the infestation, not only for the benefit of the locality where it 

 exists, but to prevent the spread of the pest beyond the known 

 infested area. This makes necessary the use of a combination of the 

 methods that can be most cheaply applied. 



