THE ROUGH-HEADED CORN STALK-BEETLE 29 



and is characterized by its large, nearly rectangular clypeus which 

 is separated from the epicranium by a distinct clypeal suture. The 

 surface of the head is smooth except for a number of rather sparse 

 punctures and is entirely devoid of either rugulse or a transverse 

 ridge. 



CYCLOCEPHALA spp. 



The only stages in the life history of Cyclocephala likely to be 

 confused with Euetheola rugiceps are the larva and the pupa. The 

 larva? of Cyclocephala are somewhat smaller than those of E. rugi- 

 ceps and of more yellowish hue. They also differ in the smooth 

 and shiny surface and yellowish amber color of the head shield and 

 in the entire absence of any trace of a median double row of modi- 

 fied bristles on the last ventral segment. The distinctive character 

 of the pupa was not fully studied in this investigation, but the 

 possibility of confusing it with the same stage of Euetheola is 

 largely eliminated by the fact that the two occur at entirely dif- 

 ferent periods of the year. Thus, at Tappahannock, pupse of 

 Cyclocephala were obtained from the last of May to the early part 

 of July, whereas those of E. rugiceps were never taken before 

 August. 



PHYLLOPHAGA spp. 



So far as adults of Phyllophaga are concerned there need be no 

 difficulty in distinguishing them from Euetheola rugiceps, while the 

 larvae may be recognized by the reduced size and triangular outline 

 of the supraanal plate, the angular form of the anal slit, the smooth 

 and shiny surface and yellowish color of the head shield, and the 

 presence of a conspicuous, sharply defined, double row of modified 

 bristles on the last ventral segment (PI. Ill, O). 



NATURAL ENEMIES 



The data on the predacious enemies of Euetheola rugiceps are 

 very incomplete, and little of importance has been added in the 

 course of this investigation. The underground habits of the species 

 render it difficult to obtain direct evidence of predatory enemies,, 

 and only a very small proportion of the individuals collected were 

 parasitized. 



At Tappahannock the fields infested with E. rugiceps were ob- 

 served to be frequented by flocks of crows, grackles, and bobolinks, 

 which were probably feeding upon the beetles, though direct proof 

 of this was not obtainable. The Bureau of Biological Survey, 

 however, has found specimens of E. rugiceps in the stomachs of the 

 crow, meadowlark. and bluebird, and of species of the closely related 

 genus Ligyrus in the stomachs of numerous birds. 



Among the possible insect foes of E. rugiceps may be mentioned 

 several species of Carabidae (ground-beetles), Asilidae (robber- 

 flies), and ants. Carabiu beetles were normally common in under- 

 ground situations and were of frequent occurrence in the places 

 where E. rugiceps has been found, but the writers have no direct 

 evidence that they attack or kill the latter, though it seems likely that 

 the smaller larvae, at least, may at times be the victims of these pre- 

 dacious beetles. As for the Asilidae, Titus (13) mentions the larva 



