ArticLe V.—Contributions.to a Knowledge of the Natural Enemies 
of Phyllophaga.* By Joun J. Davis, Entomological Assistant, Cereal 
and Forage Crop Insect Investigation, Bureau of Entomology, U. S. 
Department of Agriculture. 
INTRODUCTION 
On account of the difficulty of controlling the common white-grubs, 
which pass ninety-five per cent. of their life under ground, their natural 
enemies are of unusual importance to the farmer. No one species of 
animal can be regarded as the most important check on the increase of 
the grub, but of its insect enemies the black digger-wasps belonging to 
the genus Tiphia are undoubtedly the most generally common and wide- 
spread, and are among the most effective insect parasites of white-grubs. 
In some sections the yellow-banded digger-wasps of the genus Elis are 
abundant, and in others asilid larvae of one species or another are of 
considerable importance. Two-winged flies of the ortalid genus Pyrgota 
and others of the family Tachinidae parasitize the beetles, are generally 
distributed, and serve as significant checks. Among the native mammals 
and birds the skunk and crow stand out as models of efficiency in grub 
eradication. Diseases of various kinds are effective sporadically, but 
their occurrence is too infrequent, too local, and too dependent on 
weather conditions to make them as generally useful and reliable as the 
insects, mammals, and birds mentioned above. 
The efficiency of certain of the enemies of the white-grubs has been 
repeatedly demonstrated. During 1915 a nematode disease became 
evident in some sections, and heavily infested fields were practically 
freed of white-grubs by the action of this parasite. In another section, 
during the same year, a protozoan disease eradicated the pest in some 
fields. The black digger-wasps have undoubtedly controlled the grub in 
some sections where the pest once wrought havoc to corn crops. ee 
versely, the destruction of wild game, including birds and mammals, is 
apparently responsible in part for the increasing abundance of oe 
destructive pests as white-grubs. These insects are seldom so injurious 
or wide-spread as were the destructive broods of 1912 and 1915, and 
their superabundance at any given time or place is apparently due to a 
decrease in the natural enemies which under ordinary conditions would 
keep them under reasonable control. 
The value attached to their natural enemies in the control of the 
white-grubs is well shown by the fact that the Porto Rican sugar-growers 
* The specific synonymy of this genus here adopted is that given by Glasgow 
in his revision of the synonymy of the genus Phyllophaga Harris (Lachnosterna 
Hope)—Bul. Ill. State Lab. Nat. Hist., Vol. 11, Art. 5, Feb., 1916. 
