DISPEESIOjST of gipsy-moth larvae by the wind. 



quarantine line for experiments intended to explain the sources of 

 many infestations found under such conditions. 



Screens of poultry wire, to which tanglefoot was applied, were 

 erected in three of the selected locations along the coast and on the 

 Isles of Shoals (PL II). Those used in the New Hampshire hill ex- 

 periments were of a somewhat different type and are described 

 mider that head. The screens used along the coast (PL III, fig. 1) 

 were of ^-inch mesh poultry wire stapled to 2 by 4 posts which 

 were set in the ground and held in place at the top by guy wires and 

 wooden braces. The posts were 12 feet high and two sections of wire 

 each 75 feet long and 3 feet wide were fastened to these so that the 

 top selvage was 12 and the lower 6 feet from the ground. The 

 screens contained 450 square feet of wire and were built in three 

 25-foot sections, the middle section facing the west and the other 

 two angling from the ends about 45° to the eastward. This gave 

 the greatest exposure at all times to the northwest, west, and south- 

 west winds. A runway was attached to the posts at the bottom 

 selvage of the wire to facilitate examinations. 



HATCHING OF EGGS IN RELATION TO WIND DISPERSION OF FIRST- 



STAGE LARVAE. 



Close observations on the time of hatching of egg clusters in the 

 field have been kept since 1912 by laboratory men stationed in 

 different sections of Massachusetts and New Hampshire. The data 

 consulted were collected by Messrs. E. A. Proctor in northeastern 

 Massachusetts, J. V. Schaffner, jr., in Massachusetts south and south- 

 west of Boston, and I. L. Bailey in south-central New Hampshire. 



Table I. — First, maximum, and last dates of hatching in 1912, 1913, and 1914. 



Year. 



Northeastern Massachusetts 

 hatching. 



Southeastern Massachusetts 

 hatching. 



South-central New Hamp- 

 shire hatching. 



First. 



Maxi- 

 mum. 



Last. 



First. 



Maxi- 

 mum. 



Last. 



First. 



Maxi- 

 mum. 



Last. 



1912 



19M 



Mav 2 

 Apr. 25 



May 11 



May 11 

 May 6 

 May 15 



May 22 

 May 27 

 May 28 



May 1 

 Apr. 26 

 May 9 



May 15 

 May 10 

 May 15 



May 25 

 May 21 

 May 23 



May 1 

 Apr. 29 

 May 11 



May 14 

 May 8 

 May 16 



May 23 

 May 14 

 May 28 



The first Larvse were caught on the screen in northeastern Massa- 

 chusette M;iv 9, 19*13, and the last June 5, while the largest numbers 

 were removed between May 14 and June 1. During 1914 in the 

 same section the first larva was caught about May 10, while tho 

 largest numbers were removed from May 20 to May 27 and the last 

 June 6. One larva was caught in Hennikor, N. II., as late as Juno 

 13, L91 l. 



In a year of norma] hatching, as in 1913, wind dispersion was 

 noted aboul two weeks after first hatching and one week after hatch- 



