60 THE DISPEESIOX OF THE GIPSY MOTH. 
EFFECT OF WIND SPREAD ON THE PROBLEM OF GIPSY-MOTH 
CONTROL. 
The fact that gipsy-moth caterpillars are spread chiefly by wind 
during the time they are in the first stage and that for this reason 
the present spread of the insect is toward the northeast, northwest, 
and north has been sufficiently demonstrated. Another factor which 
enters into the problem to a greater or less extent, and which has an 
important bearing on the spread of young caterpillars by air cur- 
rents, is the altitude of the woodland in the various towns. 
Whether high altitudes are more likely to become infested in this 
way than low areas it is difficult to state, but there can be no question 
in regard to the difference in temperature of winds after having 
passed over an area of high land. For example, the cold winds which 
sweep down the Xew England coast from the northeast and east are 
not accompanied by as low temperature, nor are such winds as cold 
or penetrating in the central part of Massachusetts as they are along 
the seacoast. As high winds must be accompanied by high tempera- 
ture in order to bring about the spread of young caterpillars, it can 
be stated that after the territory on the west side of the watershed in 
Massachusetts and Xew Hampshire becomes infested to such a degree 
that large areas are defoliated, the spread of the young caterpillars 
by wind will be more far-reaching and more rapid than it has been 
at any period since the moth first became established. It is indeed 
a fortunate thing that the gipsy moth first found lodgment on the 
Xorth Atlantic seaboard, on account of the various elements which 
have worked together to restrict its spread. If the insect had first 
escaped in central Massachusetts, in Connecticut, or in Xew York 
State there would have been ample opportunity for spread in all 
directions, and it would have been difficult to restrict it to anything 
like the area which it now occupies. 
SUMMARY. 
The gipsy moth is spread by local and long-distance means. 
Local spread may be due to the transportation of caterpillars or 
egg clusters on carriages or wagons that move for only a short dis- 
tance outside the infested territory. The egg clusters may be carried 
on driftwood which floats down rivers during the spring. 
Long-distance spread may be due to the shipment of egg clusters on 
lumber products, nursery stock, or boxes from the infested territory 
to any points where such goods are unloaded. Caterpillars may be, 
and often are. carried long distances on automobiles or trolley cars, 
and cases are on record where colonies have been established in 
this way. 
