THE GIPSY MOTH OX CRANBERRY BOGS. 
periods, viz, 9 a. m. to 12 m. and 2 to 5 p. m. ; 2 and, furthermore, 
the observations of four consecutive years give substantially the same 
•results. The small number of larvae 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 fullv 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 
P 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 larvae 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 No. 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. They first eat through or between the bud scales, and then 
consume the tender undeveloped 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 cranberry plant 
showing- injury caused by first-stage gipsy 
moth larvae. 
-All observations recorded in this bulletin were made according to Eastern standard 
time. 
108485°— 22 2 
