102 
Ants can not be considered predaceous enemies of white-grubs, but 
in our cages it is evident that they have been responsible for the death 
of grubs and pupae. It is doubtful if healthy grubs are ever attacked 
by them under normal conditions, but we have seen them attacking grubs 
almost immediately after being exposed by removing a piece of infested 
sod. The ants in the cases mentioned above, were Lasius niger Linn., 
var. americanus Emery. 
According to Mr. E. G. Smyth, Mr. T. H. Jones reared larvae of an 
elaterid (Pyrophorus luminosus Ill.) upon Phyllophaga larvae in con- 
finement, and adults were taken from soil in a cane field in Porto Rico 
where the white-grubs had been present in numbers, the latter fact 
indicating that the predaceous activity observed by Mr. Jones in the 
cages is a normal habit of the larvae under field conditions. Mr. J. A. 
Hyslop has found these larvae similarly active toward white-grubs in 
tin-box cages. 
Crickets may also prey upon white-grubs, as was noticed by the 
writer at Cascade, Iowa, September 24, 1917. While following the 
plow in a sod field heavily infested with the 1917 brood of grubs, two 
species of crickets (Gryllus assimilis Fabr. and Nemobius fasciatus, var. 
vittatus De G., Caudell det.) were seen to attack the young grubs as 
these were exposed by the plow. The crickets were quite numer- 
ous, the small Nemobius probably the more common, and after attacking 
the grub they would feed on the fluids issuing from the wounds. 
Mires as Enemies or Poy~tutopHaca Larvan 
Mites, determined by Mr. Nathan Banks as Rhizoglyphus phyllox- 
erae Riley, have frequently been found infesting grubs in the field and 
are a constant cause of trouble in our breeding cages. They firmly attach 
themselves to their host, and if not removed will frequently kill the grub. 
While we have never found them as destructive in the field as in our tin- 
box cages, nevertheless there is little doubt that they do sometimes 
weaken or even kill grubs under natural conditions (55). The same 
species has been collected on white-grubs by Mr. J. A. Hyslop at Hagers- 
town, Md., and by Dr. Henry Fox at Tappahannock, Va. It is wide- 
spread, our records showing its occurrence in the United States from 
Massachusetts to Texas. Its normal food appears to be decaying veg- 
etable and animal matter. 
A pale whitish species, Tyroglyphus armipes Bks. (Banks det.), 
was found infesting white-grubs collected at Austin, Tex.; and a third 
species attacking them, which Mr. Banks determined as Parasitus sp., 
was collected by Mr. C. N. Ainslie at Springville, Utah, and at Ell Point, 
S. Dak. 
The adult May-beetles are also sometimes infested by mites, and 
specimens referred to Mr. Banks were determined as belonging to the 
family Parasitidae (Gamasidae) and to the genus Uropoda. All of the 
mites we have collected on May-beetles are in the nymphal migratory 
stages, in which they attach themselves to the beetles as a means of car- 
ee 
