31 
body, opens in an angular slit or groove which forms the lower 
border of a small plate (the supra-anal plate), the upper border 
of this plate being broadly rounded. In other words, this supra- 
anal plate has the form of a broad triangle with a widely 
rounded upper margin. In Cyclocephala the corresponding plate 
is very large , and its lower border is straight, so that the vent 
opens" here in an unbroken transverse slit instead of the angular 
one above described. These characters are quite sufficient to 
separate these larvae, but others will be given in this article 
under another head. 
LIFE HISTORY OF LACHNOSTERNA. 
Some studies of the transformations of the white grubs begun 
by me in 1886 have led to the discovery that the biography of 
these insects most generally current in entomological literature 
is erroneous and misleading in some important particulars, and 
that agricultural practices based on this inaccurate biography 
must be largely without beneficial effect. 
If I were to sav that the white grub lives for three years in 
the earth, counting from the May or June when the eggs are 
laid ; that the grub or larva gets its growth in its third autumn, 
hibernates in the earth without transforming, pupates in the 
third spring of its life, and presently emerges as an adult, I 
should repeat in substance what has been many times said be¬ 
fore; but this account would be quite inaccurate, at least as to 
the period of maturity and the time of transformation of the 
great mass of our white grubs, and might lead to unfortunate 
practical mistakes. 
In fact, all the species of Lachnosterna whose transformations 
I have observed (and to this genus the great majority of these 
grubs belong) get their full growth in spring and early sum¬ 
mer, pupate in summer and early autumn, change in the earth 
to the adult beetle in fall, and hibernate there in that stage 
without escaping, finally crawling out of the earth for their 
brief life as “ June beetles” in April, May, or June, or, rarely, in 
July. 
One practical bearing of this difference in history is easily 
seen. If the first account were correct, ground which contained 
full-grown, active, and destructive grubs in late summer and 
fall might always be safely planted, so far as the grubs are 
concerned, to corn or potatoes or any other of the numerous 
crops subject to their attack, since by spring the insects would 
be too far advanced towards pupation to do any further injury; 
but in fact this is far from being the case, for a grub active in 
fall will also, if nothing interferes with it, be destructive in 
spring and well on towards or into the summer, and will thus 
have time the following year, before reaching the term of its 
larval life, to completely destroy either corn or small grain. 
