REPORT OF THE STATE ENTOMOLOGIST I9II 47 



a consequence the pest depends largely for dissemination upon 

 the eggs or caterpillars being carried. The former may be read- 

 ily distributed, since they are deposited upon a variety of mate- 

 rials, such as tree trunks, stones, bricks, boxes, crates, tin cans, 

 and in fact almost any hard object near an infested tree or plant. 

 Even railroad cars standing near infested trees have been bur- 

 dened with eggs. Fortunately, there is a considerable chance that 

 packing boxes, building materials, etc. will, if transported and 

 infested, not be in the immediate vicinity of a desirable food plant 

 at the time the eggs hatch. This one factor probably accounts for 

 so few isolated colonies being found. Railroad cars, both passen- 

 ger and freight, rarely stand for any length of time near trees 

 which may be infested or at the time of egg-hatching adjacent to 

 desirable food plants. Consequently there is not the serious 

 danger of spread with freight and passenger trains running in 

 and out of the infested territory, as would seem at the first 

 thought. On the other hand, young trees or plants bearing eggs 

 carry with them in most instances desirable food or are very 

 likely to be set in the near vicinity of plants upon which the 

 caterpillars can thrive. This is the reason Avhy infested nursery 

 stock must be regarded as a most important factor -in carrying 

 the gipsy moth to sections remote from the infested territory. 

 The crawling powers of the caterpillar are limited. Recent 

 experiments have shown that the young caterpillars may be 

 blown considerable distances by winds, and other evidence 

 leads to the belief that under certain conditions they may even be 

 carried by birds, especially by some of the larger species. There 

 was undoubtedly a considerable local spread in the early days by 

 caterpillars which were carried on vehicles traveling out of the 

 infested region. Almost any moving object would serve this 

 purpose. Automobiles are particularly efifective and could easily 

 pick up hundreds if not thousands of caterpillars in a short run 

 through infested woods at the proper season of the year. This 

 condition prompted and justified the large expenditures by the 

 Federal Government for the purpose of freeing roadside trees 

 from the pests and thus preventing a wide and rapid dissemina- 

 tion. The adoption of this policy has greatly reduced the danger 

 of vehicles spreading the caterpillars, though the possibility of 

 this still occurring, were there to be a change in conditions, 

 should not be overlooked. 



