120 
observation goes, into more than two.* This is readily to be ex¬ 
plained on the supposition that the larger specimens are two years 
old that season and that the smaller have hatched from eggs 
laid the preceding summer. Upon this supposition the Lachno- 
sterna larva lives as a grub a trifle over two full years, changes 
to the pupa and imago at the beginning of the third year of 
its life, and emerges from the earth an adult, prepared to lay 
its eggs, at the end of this three-year period. 
The growing grubs feed, of course, only during the season of 
growing vegetation, usually retiring from the middle to the last 
of November to a depth beneath the surface varying according 
to ther severity of the winter weather, and coming up again 
within reach of food commonly some time in March or earlv 
April. 
The time and place of hibernation have their especial economic 
interest, since while in their usual winter quarters the white 
grubs are far beyond the reach of any agricultural operations. 
The distance to which they retreat in this latitude is about a 
foot and a half, if I may judge from a single observation made 
November 29, 1880, in a badly infested field of wheat in San¬ 
gamon county, Illinois. Here, around the margins of denuded 
patches,—the ground being frozen some four inches deep,—the 
white grubs were found repeatedly in numbers averaging four 
or five to the square foot at a depth varying from a foot and 
a half to two feet. In 1890 they had already come up, in the 
pastures, from their winter quarters by the 24th of March; were 
still at the surface in their usual number during the latter part 
of October; and had not wholly withdrawn by November 25— 
although at this last date most had gone beyond the reach of 
the p]ow. Notwithstanding this well-marked habit of retreat at 
the approach of winter, they occasionally linger at the surface 
and hibernate at a depth scarcely greater than that at which 
they are to be found during the summer season. 
Pupation and Formation of the Beetle .—The full-grown white 
grubs, presumed to be two years old according to the preceding 
section, will live an active life in the earth, feeding freely from 
March to June or July, during which months they change to the 
pupa a few inches under ground, in oval cells made by the grub 
by turning about in the earth. In this smooth-walled chamber 
the cuticular remnant of the last moult will be found enclosed 
with the pupa—that is, the crust of the head of the grub and 
shriveled fragments of its last skin. Our first date for this pu¬ 
pal transformation of L. in versa \s June 13, 1889, but Professor 
Perkins notest the pupation of two larvse out of several hun- 
* To verify this statement it is necessary that the observer should learn to distinguish 
species, or at least groups of species of these insects in the grub and larval stage, charac¬ 
ters for which are given further on in this treatise. Adult grubs of some of the smaller 
species might otherwise be mistaken for young of the larger ones. 
+ Fifth Ann. Rep. Vt. Agr. Exper. Station (1891), p. 148. 
