54 
have had an expert traveling throughout the United States for several 
years gathering parasites for use in the control of the white-grubs in 
Porto Rico, where they are very injurious to sugar-cane and other crops. 
The object of this paper is to place on record our preliminary 
observations, to bring together the complete records of white-grub 
enemies for the use of others in this work, and to stimulate the study 
of the beneficial species occurring in different localities. The writer is 
especially anxious to receive living parasites from all sections of the 
country, and persons able and willing to cooperate are requested .to 
notify us of that fact. 
The writer is especially grateful to Messrs. W. R. Walton and H. 
E. Smith and Dr. J. M. Aldrich, who determined most of the dipterous 
parasites, and to Mr. A. B. Gahan for the determination of the Hymen- 
optera. Thanks are due the various state and bureau officials mentioned 
hereafter in the text, who have furnished specimens used in our work. 
We also take this opportunity of expressing our appreciation of the 
cooperation and assistance of colleagues who have served at the La- 
fayette Laboratory from time to time, including Philip Luginbill, C. W. 
Creel, W. J. Phillips, R. J. Kewley, A. F. Satterthwait, H. J. Hart, F. A. 
Fenton, S. L. Mason, H. Fox, D. G. Tower, and D. A. Ricker. Photo- 
graphs for figures 8, 10, 12, 28, 30, 31, 41, and 42 of the plates were taken 
by Mr. J. H. Paine; and the excellent drawings for the text illustrations 
were, with a few exceptions, made by Miss E. H. Hart and Mr. W. R. 
Walton, of the U. S. Bureau of Entomology, for which the writer ex- 
presses grateful acknowledgment. The writer is further indebted to his 
brother, H. A. Davis, for the lettering of charts I and IJ. 
To Dr. S. A. Forbes, the writer wishes to express his gratitude for 
the inspiration and encouragement received when as a member of the 
staff of the State Entomologist’s office he first attempted studies on 
white-grub enemies, and for the opportunity afforded for the publication 
of this paper. 
EcoLoGicaAL CONSIDERATIONS 
Although this paper is intended primarily to present the known 
facts relative to the individual enemies of Phyllophaga, it seems desirable 
briefly to note some of the relations existing between the many parasites, 
hyperparasites, and predators, and their hosts. The two accompanying 
charts present these facts graphically and require but few words of 
explanation. 
Chart I shows in a concise form the enemies of Phyllophaga from 
egg to adult. : 
Chart II is a diagramatic illustration of the relations existing be- 
tween Phyllophaga and its enemies, but does not take into consideration 
the interrelations of Phyllophaga and other beetles such as Cotalpa, 
Cyclocephala, and Ligyrus, which are attacked by some of the same 
enemies, since this would complicate and confuse the diagram. 
