CAUSES AFFECTING DISTEIBUTION. 99 



at a distance of a mile or more from other infested localities. 

 When the action of the regulative influences which at first 

 checked the increase of the moth and the limitation of its 

 powers of locomotion are considered, it seems improbable 

 that the moths could have spread over thirty townships in 

 less than twenty years unless transported by some human 

 agency. 



The Connection of Distribution and Population. 



The study of the infested territory made in 1891 showed 

 that the most densely infested areas were very nearly coin- 

 cident with the centres of population. In other words, the 

 moth colonies were larger and more numerous in or near 

 thickly populated districts. (See map TV,) It was noted 

 that as the inspection receded from Medford, where the moth 

 was first introduced, the towns were less and less infested. 

 When, in this inspection, the centre of a town next adjoin- 

 ing Medford was reached many moths were found. As the 

 centre was passed they grew less numerous until few, if any, 

 appeared along the highways. Such trees as were found 

 infested were generally near farm-houses and other resi- 

 dences. On approaching the next town the moths were 

 again found in considerable numbers, although not as nu- 

 merously as in the first town. After the second town was 

 passed none were found upon the country roads leading 

 farther out. This led to the hope that there were no 

 moths in the region beyond. But an inspection of the next 

 town revealed a few, while in the towns beyond none were 

 found. 



Outside of Medford the moths were most numerous in 

 portions of the cities lying nearest to that town, such as 

 Maiden, Chelsea, Somerville and Cambridge. Next, the 

 larger towns, as Melrose 5 Arlington, Belmont and Win- 

 chester, and the more distant cities, Lynn and Salem, were 

 most infested. Comparatively few moths were found in the 

 more sparsely settled towns, like Lynnfield, Eeading and 

 Lexington. This distribution of the moth along the roads 

 and over populated districts led to the assumption that 

 man was accountable for its diffusion as well as its intro- 

 duction. 



