6 BULLETIX 1093, U, S. DEPAETMEXT OF AGRICULTURE. 



Finally, the whole surface was covered with a coating of com- 

 mercial sticky tree-banding material about one- fourth inch in thick- 

 ness to serve as a trap for the caterpillars. 



Later, improvements were made by setting the traps practically 

 level, with an additional center support running longitudinally and 

 serving as a ridge, which gave a slight pitch to either side, forming ' 

 a perfect watershed. They were also raised to stand about 2 feet 

 above the bog surface, particularly to facilitate inspection. 



No. 10, the solid-surface vertical trap, was constructed of wall 

 board, with the upper edge of the trap 9 feet above the surface of 

 the bog. Twelve 8-inch holes were cut through the wall board and 

 covered with ]-inch mesh wire screen in order to reduce the force 

 of the wind, but more particularly to prevent a cushion of air from 

 forming in front of the trap. The whole surface, wall board and 

 wire, was given a coating of commercial sticky tree-banding material 

 as in the case of the horizontal traps. (PL III. Fig. 1.) Trap No. 11 

 was constructed in the same manner as Xo. 10. with the exception that 

 three-fourths inch mesh wire netting was used for a surface. (PI. 

 Ill, Fig. 2.) All traps, with the exception of Xos. 10 and 11, were 

 erected with the longer dimensions running east and west. Xos. 10 

 and 11 were erected verticall3% facing east and west. In order to 

 obtain information regarding the numlier of caterpillars and how far 

 they were blown onto the bog. these traps were located at varying 

 distances from the bog border. 



RECORD OF TRAP OBSERVATIONS. 



. Trap observations have yielded information in regard to the num- 

 ber of caterpillars carried by the wind and as to the conditions under 

 which they are carried. 



The time of hatching the gipsy moth caterpillars is governed 

 by the temperature. It is evident that in order to control infestations 

 on bogs careful attention must be given to this factor. (See Table 1.) 



Table 1. — The variation of time in Imtching and dispersion of gipsy moth 

 caterpillars during the period covered by observations at Muddy Pond Bog, 

 Carver. Mass. 



Year. 



First 



hatching 



noted. 



First 



larvae 



talren on 



traps. 



Time of maxi- 

 mum dispersion 

 on traps. 



Time be- Time be- 

 tween first tween first 

 hatching trap record 



and maxi- 

 mum dis- 

 persion. 



and maxi- 

 mum dis- 

 persion. 



1916 

 1917 

 1918 

 1919 



May 9 

 19 

 7 

 6 



May 22 

 26 

 10 

 15 



May 25-26. . . . 

 June -3, 4, 5. . . 

 May 1.5-16.... 

 May 18, 19, 20 



Days. 

 16-17 

 15-17 

 8-9 

 12-14 



Days. 



8-10 



5-6 



3-5 



