COMMON WHITE GRUBS. id: 
and remain there feeding and mating till just before dawn, when 
they return to the soil, only to reappear the following evening. 
When abundant the beetles are capable of defoliating large acreages 
of timber, often resulting in the death of many of the trees thus 
attacked. In 1911, 40-acre tracts of timber were completely defoli- 
ated by the beetles in southwestern Wisconsin. According to wit- 
nesses, the dropping of excrement and of detached leaves at night, 
when the beetles were feeding, sounded like hail. The following year, 
1912, numbers of dead and dying trees were observed in these timber 
tracts, their death in most cases doubtless resulting from the loss of 
foliage the year before. 
Not only do the different species have individual food preferences, 
but they also differ in the dates of emergence, some appearing early 
and remaining throughout the season, others appearing about mid- 
season and remaining only a few weeks. Some species, also, occur 
only at the higher elevations, while others appear to be common only 
at the lower levels; but whether this difference is due to a difference 
of elevation or to the character of the flora, or to a combination of 
the two, has not as yet been determined. 
The beetles (fig. 2) prefer to deposit their eggs in ground covered 
with vegetation, in the immediate vicinity of timber, usually choosing 
for this purpose the more elevated parts. For these reasons the grubs 
are ordinarily found most abundant in the higher portions, especially 
near wooded tracts, of fields of timothy (fig. 8), blue-grass sod, and 
small grains, or in any ground which during the previous year was 
in one or another of these crops. 
The eggs (fig. 7, a, 6, ¢) are pearly white and when first laid are 
elongate, measuring about one-tenth inch in length, but six or seven 
days after oviposition they become swollen and almost spherical. 
They are deposited in the soil at a depth ranging from 1 to 8 inches, 
within oval cavities in the center of balls of earth, the particles of 
earth forming the balls being held together by a glutinous secretion 
supplied by the female beetle. 
The very young grubs seem to prefer decaying vegetation, although 
under certain conditions, especially when they are very numerous, 
they will attack living roots, as was the case’ in Wisconsin in 1911 
when the young grubs damaged timothy fields (fig. 8). As might 
be expected, the grubs do the greatest amount of damage in their 
second year and to the early plantings in their third year. While 
grubs show-a preference for certain food plants, from our present 
data the grubs of different species do not appear necessarily to have 
different food habits. We have no authentic records of injury to 
such crops as clover, alfalfa, and buckwheat, and from all observa- 
tions small grains are less attacked and injured than are corn, tim- 
othy. strawberries, and potatoes. 
543 
