* REPORT OF THE DIRECTOR, 1922 31 
border and as the insect issues from this rough, densely wooded area 
into the more open sections of the Hudson valley, there to establish 
a line beyond which the insect shall not be allowed to maintain itself, 
the precise location of this barrier zone to be determined by a care- 
ful examination of the wooded and cultivated areas of the Hudson 
and Champlain valleys and the northern boundary of New York 
State westward to Lake Ontario for the purpose of establishing a 
zone where the insect can be held most economically and success- 
fully. The establishment of a barrier zone would be a gradual 
process extending through a series of years and determined in large 
measure by the westward spread of the moth. The entire line 
extending from some point on Long Island Sound northward and 
westward to Lake Ontario, would be shorter than the present 
boundary of the infested area, along all of which repressive work 
is being conducted. The maintenance of a successful barrier zone 
would mean immunity from gipsy moth ravages for all of our terri- 
tory west of that area, not to mention the protection given to other 
States, provided isolated infestations, which presumably will be 
found from time to time beyond this line, are exterminated. The 
cost of maintaining such a zone would be much less than attempts to 
control the gipsy moth over a considerable proportion of New York 
State, if it became infested, as is to be expected, unless some such 
plan is put into practice and there would be in addition to the cost 
of controlling the infestation, the enormous and widespread losses 
resulting from severe injuries to forest and shade trees throughout 
the infested area. There is every reason for believing that the Fed- 
eral Government, in view of the national aspects of the problem, 
would cooperate in a very substantial way in maintaining this barrier 
zone, and it is gratifying to state that most of the experts thoroughly 
cognizant with the situation agree as to the wisdom of testing possi- 
bilities in this direction. 
The apple and thorn skeletonizer (Hemerophila 
parianaClerck). This European insect found well established in 
Westchester county in 1917 and remaining in that area with com- 
paratively little spread in this State until the past season, has greatly 
extended its range north in the Hudson valley as shown by our 
investigations. It is now well established on both sides of the Hud- 
son river northward to and including the southern portions of both 
Albany and Rensselaer counties and in these latter areas, it was so 
extremely numerous in unsprayed orchards, as to practically defoli- 
ate the trees toward the end of the summer. This stripping, as 
