554 NEW JERSEY AGRICULTURAL COLLEGE 



Unfortunately the hnman element comes into the problem, and thus 

 a spread of hundreds of miles in a year is among the possibilities. 

 While the larvse are small and susp^-nd themselves readily by threads, 

 many of them are carried away by pedestrians walking l>eneath the 

 trees. When the insects are discovered the natural tendency is to 

 brush them off to get rid of them, no matter whcrc^ or how far away 

 from the place where they were gathered. When they fall upon car- 

 riages, wagons or similar conveyances, the distance to which they may 

 be carried is much greater, and on a trolley car the range is yet more 

 extensive. Yet even the trolley range is a limited one and confined to 

 a definite line. Railroad trains do not often travel on a line over- 

 shadowed by trees, so these are not so greatly important. Automo- 

 biles, however, go everywhere, and may carry young caterpillars for 

 many miles in a single day. If at the end of a day's run the young 

 larva? find food convenient, and are in sutficient number to have both 

 sexes represented, a colony may be established. No doubt many indi- 

 viduals have been so carried, have developed and have died for lack of 

 a mate. It is only by a fortunate combination that a reproductive 

 colony can be established in this way. but this combination may happen 

 at any time, and perhaps has happened, for the present outer limits of 

 infestation are by no means established. 



Wlien the fuU-gTown caterpillars wander along the line of a railroad 

 the danger becomes much enhanced. Freight cars on sidings, cord- 

 wood to be loaded and carried away, boxes, bales, barrels, crates and 

 other carriers serve as excellent places for pupation, and from a single 

 pair carried off in this way a colony could readily be established miles 

 away. That this is not a remote contingency is shown by tire fact that 

 moths and egg masses were observed in some numbers on a railroad 

 station building in the infested district, and freight cars were observed 

 on sidings close to infested trees. 



The danger of rapid spread increases as the infested area increases, 

 and it is greater now than it has been at any time since the insect has 

 established itself in this country. 



At present the probability of an early spread to the New Jersey line 

 is slight; the possibility exists of entrance through the medium of 

 freight, freight cars or plants from the infested districts. Much now 

 depends upon the amount of work that can be accomplished next 

 winter under the new law in Massachusetts. 



