April, ’20] 
DAVIS: GREEN JAPANESE BEETLE 
187 
or early April and resumes feeding. The older larvae complete their 
growth by early June when they prepare earthen cells in which they 
transform to the pupa and about two weeks later to the adult. Pre¬ 
vious to pupating the grub is in the prepupa or dormant stage for a 
period of a week or ten days, and after transforming to adult it usually 
remains in the cell another ten days to two weeks before coming out 
of the ground. Like the related leaf chafers this insect pupates within 
the larval skin, the skin splitting along the back almost the entire 
length. 
The first beetle issues the last of June and the maximum period of 
emergence is during the latter part of July. The life of the individual 
beetle varies considerably, averaging from one to ten weeks, but 
beetles occur over a period of about four months, abundantly over a 
period of two to two and one-half months. 
After issuing the beetles feed for several days to a week before mating. 
Mating and egg laying is continued at irregular intervals, the eggs 
being laid by preference in uncultivated places such as grassy fields or 
grassy and weedy areas along roadways, in moist but not swampy 
ground, and in soil rich in humus, each beetle laying an average of 60 
eggs. The young grubs hatching from the eggs some two weeks later 
feed on decaying matter in the soil and to a less extent on living plant 
roots and late in fall they form earthen cells, in which they pass the 
winter. 
The beetles are omnivorous, resistant to unfavorable conditions, 
strong fliers, and very active during warm, clear days. While they 
may remain above ground on plants during the night they usually 
feed only during the day; they are sluggish in cool or damp weather, 
but exceedingly active on warm, sunshiny days and fly quickly at the 
least disturbance, seldom going far into thickets, except on the outside 
foliage and never, from our observations, do they go into woodland or 
lay their eggs within wooded areas. They prefer grassy or weedy 
ground, unshaded by thickets or trees, to lay their eggs, and favor 
moist loamy soil in preference to dry sandy soil or swampy areas. 
Importance as a Crop Pest 
The insect is not injurious in the grub stage, partly because the grubs 
are actively feeding at a time when crops are least likely to be injured 
and partly because they feed as freely or more so on decaying matter 
as on living roots. 
The beetle is a serious menace to small fruits, orchards, cereal and 
forage crops and to ornamentals. It is almost omnivorous, feeding, 
according to our records, on more than 120 plants. It feeds on weeds 
and wild shrubs of many kinds, such as smartweed, elder, sassafras 
