RESULTS OF SCOUTING WOODLAND AREA. 59 
establishment of the species, although the selection of areas contain- 
ing the most deciduous growth in both towns aided in securing more 
satisfactory data. 
Wareham was found infested in 1905, and if the town had been 
located along the line of prevailing winds at the time the gipsy-moth 
caterpillars were in the first stage, the woodlands would probably be 
as badly infested as those in towns an equal distance north or north- 
east of the original infested area. This is not the case, however, 
which indicates in itself that unfavorable food and practical im- 
munity from winds favorable for spread have worked to the advan- 
tage of this town. 
The same statement can be made of both Gardner and Grafton, 
which were found infested in the winter of 1907-8- It is true that 
there are a considerable number of small roadside and orchard infes- 
tations in these towns, particularly in Grafton, but travel is heavy 
during the early summer and an excellent opportunity is offered for 
the spread of the larva? on vehicles and automobiles. If wind spread 
were not a prime factor in distributing the gipsy moth, the woodland 
in Grafton should be more heavily infested than the wooded area 
examined in Milton, N. H., because the latter town is much farther 
from the original center of infestation, and was first found infested a 
year later. 
It is practically impossible to explain the origin of many separate 
infestations; but taking the woodland areas examined and studying 
them in relation to each other and in relation to the badly infested 
area, it is evident that the theory already given concerning wind 
spread is confirmed. 
It is surprising, when all the facts are considered, that so much 
good work has been done in controlling the gipsy moth in many of 
the infested towns. Large numbers of cases are on record where all 
the infestations in a town have practically been cleared of this 
insect in a single year ; but, owing to general wind spread, as many 
and usually more colonies have been found in other parts of the 
same town the next year. This is one of the discouraging features of 
the work and renders it extremely difficult to control the insect in 
towns which are most subject to natural spread by the wind. It is 
obvious that if this is to be brought about, bad colonies must be 
subdued, particularly those which are nearest the outside border of 
infestation, because, as has already been pointed out, the farther the 
larvae are carried by the wind the less the chance becomes for them to 
establish the species, owing to their wide separation from other speci- 
mens and the limited opportunity of their finding suitable food for 
full development. 
