8 COMMON WHITE GRUBS. 
dant and injurious species in those localities is uniformly three 
years. We may, therefore, be reasonably certain that in 1914 the 
beetles will again be unusually abundant, and the year following 
(1915) the grubs will as a consequence be exceedingly abundant and 
destructive unless their numbers are materially reduced by natural 
enemies, by artificial means, or by adverse climatic conditions. 
LIFE HISTORY AND HABITS. 
Our knowledge of the life histories of the white grubs of the genus 
Lachnosterna is very meager. There is only one published record, 
involving a single species, in which an individual belonging to this 
genus has been reared from egg to adult. In the case of this species 
(L. arcuata Smith) the life cycle in the latitude of Washington, D. C., 
Fic, 5.—A cornfield showing characteristic injury by white grubs, Lynxville, Wis., 
1912. (Original.) 
proved to be three years.1 From observations reported by Forbes, 
and from our own observations and rearing experiments, it appears 
quite certain that in the Northern States the total life cycle of the 
more injurious species is three years. However, in the case of ZL. 
tristis Fab., a small species, and one which we have recently reared 
from egg to adult, the life cycle is only two years. Mr. W. R. Dicke- 
son, of Austin, Tex., writing of the damage by Z. farcta Lec., says, 
“One year the grub bothers us and the next year the May beetle,” 
which is circumstantial evidence that this species has only a 2-year 
cycle in Texas. The total life cycle in all the species occurring in the 
Southern States may be only one or two years, and in the central 
1U. S. Dept. Agr, Diy. Ent: Bul. 19, n: ser. p. 77, 1899: 
