12 



SEASONAL HISTORY. 



The moths fl}- in New England from the Ist to the 20th of July, the 

 time varying- with the condition of the season. In 1898 the height of 

 the flying season is said by Fernald and Kirkland to have been July 16, 

 in 1899 Julv 8, and in 1902 July 11. It is a night-flying insect, and 

 onl}" a few are ever seen on the wing in the daj^time. Soon after sunset 

 a few begin to fly, the number increasing as it grows dark, and from 



Fig. 4.— Winter web of the brown-tail moth. (After Kirkland.) 



10 o'clock to midnight the}' swarm to the greatest extent. They are 

 strong fl3'ers, and are attracted to light (see flg. 3). So great have been 

 their numbers in the infested region that the sides of red brick build- 

 ings near electric lights have appeared perfectly white. It is at this 

 time that the great spread of the species occurs, and the reason that 

 the direction of the spread has been greatest toward the northeast has 

 been the fact that the prevalent night winds at that time of the year 

 seem to have been from the southwest. Aside from actual flight, the 



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