FEEDING HABITS OF THE JAPANESE BEETLE. 7 
Figure 3 is a graphic representation of the percentages of females 
1 two series of collections made from Yellow Transparent apple 
trees July 18, 1921. The two curves follow much the same course 
and can be considered together. The first collection was made at 
5 a. m. and the last at 9 p. m. (though the curve ends with the 7 
o'clock collection). Until after 8 a. m. less than 20 per cent of the 
beetles collected were females. During the forenoon there is a 
decided increase in the proportion of females collected. Between 
10.30 a. m. and 2 p. m. from 40 to 47 per cent of the beetles collected 
were females. From 2 to 4 o'clock the percentage of females decreases 
to about 20 per cent. Only 15 to 20 per cent of the beetles collected 
between 5 and 9 p. m. were females. 
Tall-growing herbaceous plants, shrubs, and trees are much less 
heavily infested with the beetles between 4 p. m. and 9 a. m. than 
they are during the middle of the day. From the data presented in 
Figures 1,2, and 3 it is evideiit that toward evening there is a more or 
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Fig. 3.— Per cent of female beetles in collections of Japanese beetles from Yellow Transparent apple, 
July 18, 1921, at Riverton, N. J. 
less definite movement of the female beetles from the tall to the 
low growing food plants, and also to the ground for the deposition of 
their eggs. It is also to be noted that Tow-growing plants such as 
smartweed maintain a higher proportion of females to males through- 
out the day than do the taller shrubs and trees. As the females 
move from the tall to the low growing species there is a complemen- 
tary movement of the male beetles to the lower-growing plants. 
This change of location by the males is much less definite and com- 
plete than that of the females. However, in making hourly collec- 
tions of 100 or more beetles it was found that it was often difficult to 
collect the required quota on apples and grapes in the early morning 
and late evening, while at midday thousands could have been col- 
lected on the same plants. These daily movements of the beetles 
may in a measure account for the fact that certain plants or groups 
of plants may be heavily infested for a period of time and then 
become free from the infestation, which in some cases does not recur 
during the season. 
RATE AT WHICH THE BEETLES FEED. 
Observations were made for the purpose of determining the average 
length of time which the beetles spent in feeding on various plants 
and also the rate at which they consumed the foliage. During a 
