April, '16] DAVIS: WHITE GRUB INVESTIGATIONS 263 



Trout Lake for four years approximate the combined temperatures 

 at Lafayette for three years. It is not improbable that we will find 

 the length of the life cycle of L. ulkei, which is the southern analogue 

 of L. grandis, to be but two years at Auburn, Alabama, where we have 

 experiments started in collaboration with Dr. W. E. Hinds. From 

 our present data it appears that the more important economic species 

 in the southern states will have a two-year cycle. It is easy to under- 

 stand why a species should have a three-year life cycle in the latitude 

 of Indiana and a four-year cycle in northern Wisconsin, where the 

 season is so short, and, on the other hand, why the same species, in the 

 southern states where the growing season is much longer, should 

 require but two years to complete its growth. It is, however, puzzling 

 to find that the same species in the same cage may complete its cycle 

 in two years in one case but require three years in another. 



We have already established life-historj^ cages in cooperation with 

 various entomologists in different parts of the country and it is hoped 

 that eventually we can have cages established in every state in the 

 Union. In 1914 and 1915 we started a number of cages at Trout 

 Lake, Wisconsin, in cooperation with the Wisconsin State Board of 

 Forestry and Mr. W. D. Barnard in charge of the state nurseries at 

 that point. The past spring we established cages at Auburn, Ala- 

 bama, in cooperation with Dr. W. E. Hinds; at College Station, Texas, 

 in cooperation first with Prof. Wilmon Newell and at the present with 

 Prof. F. B. Paddock; and at Victoria, Texas, in cooperation with Mr. 

 J. D. Mitchell, through the courtesy of Dr. W. D. Hunter. Life 

 cycle cages have also been established at two stations of this division, 

 namely at the Greenwood, Miss., station in charge of Mr. C. F. Turner 

 and at Columbia, S. C, in charge of Mr. Philip Luginbill. 



Briefly the life-history of the economic species of Lachnosterna in 

 our latitude is as follows: The eggs are laid in the ground, most often 

 in ground covered with vegetation such as blue grass, timothy and 

 small grain, in balls of earth (Plate 14, fig. e), one egg in a cavity shghtly 

 larger than the egg, in the center of the earthen ball which is held 

 loosely intact by a glutinous fluid secreted by the female. Individual 

 females lay between 50 and 100 eggs or even more and our averages 

 from many records in confinement, which probably do not offer ideal 

 conditions, are more than 50 per female. The grubs hatching from 

 these eggs several weeks later feed on tender rootlets and decaying 

 vegetation in the ground until fall when they go deeper into the soil, 

 forming a small earthern cell in which they pass the winter. They 

 return to near the surface early in May of the following spring and it 

 is this season that the grubs are most active feeding. The grubs dis- 

 continue feeding about the first of October of the second year, going 



