THE GIPSY MOTH CTX CKANBEEEY BOGS. 



periods, viz, 9 a. m. to 12 m. and 2 to 5 p. m. ;- and, furthermore, 

 the observations of four consecutive years give substantia 11}^ the same 

 results. The small number of larvse dispersed from 12 m. to 2 p. m. 

 is not due to lack of favorable conditions either of temperature or 

 wind velocity, for the mean temperature and wind velocity for that 

 period of the day have both been found very favorable for heavy 

 dispersion. The two periods of dispersion are due to a movement in 

 search of food and are discussed more fully under the heading 

 " Feeding habits on white-oak foliage " (p. 10). 



The data from the traps secured from 1916 to 1919 prove that in 

 order to have caterpillars dispersed in large numbers it is essential 

 to have, first, a " medium " to 

 " heavy " infestation ; second, a 

 temperature above 70° F.; third, 

 a wind velocity of from 8 to 15 

 miles per hour. It has been found 

 that a fairly steady wind blowing 

 10 to 12 miles per hour will dis- 

 perse more larvae, other condi- 

 tions being favorable, than wind 

 of higher velocity which blows 

 intermittently^ 



FEEDING HABITS ON CRAN- 

 BERRY FOLIAGE. 



Experiments have determined 

 that under laboratory conditions 

 gipsy moth larvse can not be suc- 

 cessfully carried through the sev- 

 eral stages on cranberry foliage 

 alone. This information was ob- 

 tained in 1914 by F. H. Mosher and recorded in Bulletin Xo. 250 of 

 the U. S. Department of Agriculture. In obtaining this information 

 Mr. Mosher used feeding trays devised by W. F. Fiske, formerly of 

 the Bureau of Entomology, with cranberry foliage inserted in crook- 

 necked vials, filled with water, in order to keep the food fresh. 



Bog observations have shown that the young first-stage larvae begin 

 their feeding on cranberry by attacking the contents of the terminal 

 buds. The}^ first eat through or between the bud scales, and then 

 consume the tender undeA^eloped leaves within, leaving nothing but a 

 shell formed by the bud scales. (Fig. 3.) By the time the cater- 

 pillars have reached the second stage the terminal buds not already 



Fig. 3. — Terminal bud of cranbenv plant 

 showing injury causpd by flrst-stage gipsy 

 moth larvae. ' 



-All observations recorder] in This bulletin were made according to Eastern standard 

 time. •• 



10848o°— 22 2 



