DISPERSION OF GIPSY-MOTH LAEV^ BY THE WIND. 



9 



borne, however, by northeast and southeast winds from beach infes- 

 tations 1 mile or more distant. This screen was inspected in May by 

 Dr. Howard and Dr. Paul Marchal. 



Table II. — Dates and numbers of newly hatched caterpillars caught on screen, with tem- 

 peratures, direction of wind, and velocity of wind, at Salisbury Beach, Mass., in 1913. 



Date and time removed. 



Number of 



Maxi- 



Minimum 



caterpil- 

 lars caught. 



temper- 

 ature. 



tempera- 

 ture. 





°F. 



°F. 



C 1 ) 



54 



49 



2 



62 



52 



0) 



49 



44 



3 



57 



50 



0) 



60 



56 



P) 



70 



59 



19 



68 



62 



71 



64 



49 



15 



44 



42 



13 



54 



50 



< l ) 



O 



( 2 ) 



25 



64 



58 



30 



66 



55 



10 



60 



51 



C 1 ) 



52 



48 



12 



58 



54 



(•) 



56 



52 



C 1 ) 



53 



51 



16 



59 



57 



0) 



51 



48 



P) 



48 



47 



16 



64 



53 



3 



72 



64 



11 



76 



62 



18 



77 



62 







72 



62 



1 



79 



72 







62 



56 



1 



70 



62 



286 



Average between 9 a. m. 

 and 5 p. m. 



Prevailing 

 wind direc- 

 tion. 



Wind veloci- 



ity, in miles 



per hour. 



May 8 



May 9, p. m 



May 10 



May 11, a. m 



May 12 



May 13 



May 14, a. m 



May 15, a. m. and p. m 



May 16, p. m 



May 17, p. m 



May 18 



May 19, p. m 



May 20, p. m 



May 21, p. m 



May 22 



May 23, p. m 



May 24 



May 25 



May 20, p. m 



May 27 



May 28 



May 20 



May 30, p. m 



May 31, p. m 



June 1, a. m. and p. m. 



June 2, p. m 



June 3, p. m 



June 4, p. m 



June 5, p. m 



Total 



S.and SE... 

 W. and SW . 



NW 



NW 



NW.andSE 



SW 



NW 



W. and SW. 



NE 



E.andNE.. 



11 to 15 

 8 to 11 

 18 to 22 

 15 to 18 

 8 to 11 

 10 to 13 

 13 to 17 



7 to 9 



8 to 12 

 8 to 12 



W. and NW 

 NW.andW. 



SE 



E.toNW... 



NW SW., 



and E. 



N.toE 



E.andSE.. 

 NW to E . . . 

 E 



n.: 



NW 



W.andNW. 

 NE to NW . 

 SE toSW... 



NW 



SW 



NW. to E... 

 E.toS 



IS to 23 



15 to 20 

 8 to 12 



6 to 8 

 2 to 5 



7 to 10 



7 to 11 



6 to 10 



8 to 12 

 8 to 11 



19 to 23 

 17 to 21 

 8 to 12 



16 to 20 

 16 to 20 

 15 to 19 

 12 to 16 



7 to 11 



1 No examination. 



- No records. 



It will bo noted from Table II that 266 caterpillars were caught on 

 450 square feet of wire, and most of these on days when the winds 

 blew from the northwest, west, or southwest, namely, May 14 to 19, 

 May 15 to 17, May 19 to 25, May 20 to 30, etc., while fewer were 

 caught when the wind was from the northeast and southeast. This 

 may be explained by thelighl infestations 1 mile or more to the north- 

 east and southeast; also il will be noted thai, winds from these direc- 

 tions along the coasl are accompanied by much lower temperatures, 

 hich time the caterpillars spin less actively. 



Many of the small larvae were taken on the posts and crosspieces of 

 the structure; thus of the 25 caught May 19, 18 had lodged in this 

 manner and were living when removed. Others were swinging by 

 threads on flie east side of wire, where they bad blown through the 

 1 1 1 f •- ! i from the west, the threads having eaught in tanglefoot. 



96810° Bull. 27:5 15 2 



