188 
Whatever the length of Hfe in the grub stage, all our most 
abundant species of Lachnosterna begin to pupate in June or July 
in central Illinois, and begin to change to the beetle in August or 
September, remaining, with rare or doubtful individual exceptions, 
under ground in this stage until the following March, April, or 
May. They then emerge from their winter quarters, feed on the 
leaves of various trees, and pair and lay their eggs in the earth in 
June and July. An exception should perhaps be made, provisionally, 
of L. tristis, concerning which my records are unusually imperfect, 
agreeing, so far as they go, with those of the other species of our 
list, but stopping short before the middle of June. That is, we have 
an abundance of the beetles collected from the latter part of March 
through April and May and into early June, most frequently, how- 
ever, in May, but have no collections in any stage at any date later 
than June 5. Four of our lots of tristis, collected in March and 
April, were beetles taken from the earth, which must have trans- 
formed the preceding summer or fall. 
Pupae of the above species have been taken by us from their 
underground cells only in June, July, August, and September, and 
the adult beetles have been found under ground in the cells where 
they originated, in August, September, October, and November, and 
again in April and early May. Adults of various species have been 
seen pairing in May, and in one case in June, and eggs of seven of 
these species — tristis being omitted — have been secured in June and 
July, much the greater part of them in the former month. So far 
as my rather scanty records go, the eggs may be expected to hatch 
from ten days to four weeks from the time of deposit. My dates 
for the hatching of eggs of known species are, for inversa, June 23 
and July 11 ; for fusca, June 27; for implicita, July 16, 21, and 24, 
and August 7; and for hirticula, July 7. 
From this it will appear that white-grubs found in the earth 
beyond the middle of September will not change to the beetle that 
year, but, barring destruction by parasites and other fatal accidents, 
may be- expected to pass the winter as grubs and to continue in 
that stage at least until the following June. This is a point of 
special economic interest, since the owner of infested fields needs to 
know whether the grubs in the ground during the latter part of the 
season will continue there in dangerous numbers during the follow- 
ing spring, or whether he may expect relief from their injuries by 
reason of their change to the beetle. 
The data of my collections, when taken in the aggregate for 
several years, give little indication of any fixed order of succession 
