114 THE GYPSY MOTH. 



frequently crawl to other trees, and if later these trees are 

 sprayed many of the caterpillars crawl still farther. It is 

 almost impossible to avoid scattering the moths when spray- 

 ing is resorted to, which makes it necessary to spray all 

 vegetation near an infested spot, that the scattering cater- 

 pillars may find poisoned food. 



As the work of burlapping has progressed since 1891 the 

 proportion of caterpillars seeking the shelter of the burlap 

 appears to have diminished. Many either remain in the 

 tops of trees or seek out places near the ground in which 

 to secrete themselves. There also seems to be a tendency 

 to scatter farther and farther from the infested localities. 

 These habits may have been induced by the frequent dis- 

 turbing of the caterpillars in the work of burlapping, or here 

 may be another illustration of the survival of the fittest. 

 When the caterpillars are very young and while the workmen 

 are placing the burlap bands about the trees they are likely 

 to dislodge some of the caterpillars which, falling upon their 

 clothing, may be carried about from place to place. To lessen 

 the risk of such carriage the workmen in summer are dressed 

 in a uniform suit of a light color so that any dark object 

 falling upon them may contrast strongly with their clothing. 

 The men are also cautioned to examine carefully each other's 

 clothing when leaving an infested place. Notwithstanding 

 this precaution it is possible that a few localities from which 

 the moths have been entirely exterminated have become re- 

 infested in this way, for occasionally a place in which no 

 form of the moth has been found for a year or two becomes 

 again infested. In such cases from one to three or four 

 caterpillars have been found during the season, not a suffi- 

 cient number to indicate that eggs had been laid there in the 

 previous season. 



The Distribution Restricted and Changed. 

 As far as the work of extermination has proceeded it has 

 radically changed the distribution of the moth. It is often 

 the case that the most persistent and thorough work will not 

 exterminate the moths from a locality in one year. It is 

 necessary to search a locality for several years in order to 

 be assured that the moths are all destroyed and no seed is 



