BULLETIN 115i, U. S. DEPARTMENT OF AGRICULTURE. 
weed and other low-growing plants. These collections were made 
August 18 to 24, 1921. Between 7 and 10 o'clock in the morning- 
the females constitute between 20 and 32 per cent of the beetles 
present on the plants. There is a gradual increase in the percentage 
of females until it reaches nearly 40 per cent in the 1 o'clock collec- 
tion. This proportion is not increased, nor does it fall below 30 per 
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FlQ. 1.— Per cent of female beetles in collections of Japanese beetles from smartweed, mercury 
weed, evening primrose, and mallow, August 18 to 24, 1921, at Riverton, N. J. 
cent until after 6 p. m. In the evening the females constitute about 
25 per cent of the beetles on the plants, which is nearly the same 
proportion found early in the morning. 
In Figure 2 are shown the percentages of females in two series of 
collections, one of which was made from field corn July 18, and the 
other from grape and althea between August 22 and August 24, 
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FlQ. 2.— Per cent of female beetles in collections of Japanese[beetles from corn, Julv IS, and from grape and 
rose of Sharon, August 22 to 24, 1921, at Riverton, N. J. 
1921. In the collections made from corn before 8 a. m. and after 
6 p. m. the females constituted less than 20 per cent of the total 
number of beetles. Between 11 a. m. and 1 p. m. the proportion 
of females to males was highest. In the 11 o'clock and 1 o'clock 
collections over 40 per cent of the beetles were females. On grapes 
the percentage of the beetles which were females is less than 20 per 
cent in the collection made before 9 a. m. and after 6 p. m., and it 
varies between 30 and 40 per cent in the collections made between 
10 a. m. and 4 p. m. 
