80 DEPARTMENT BULLETIN 1267, U. S. DEPT. OF AGRICULTURE 
of a robber-fly (Zax lateralis Macq.) as an enemy to this and other 
scarabaeids. At Tappahannock the junior writer observed the larva 
of a similar or closely related form preying upon larve and pupe 
of a species of Phyllophaga, but never found it attacking those of 
EL’. rugiceps. Ants were found to attack and kill any larve of the 
latter or of other scarabaeids that chanced to be exposed on the 
surface, and it is reasonable to suppose that they would do the same 
thing underground, an inference which is supported by the observa- 
tion that rarely, if ever, were scarabaeid larve of any kind en- 
countered in the vic uty of ant colonies. 
In the junior writer’s experience the most frequent enemies are 
certain mites which attach themselves to the body surface. That 
these mites derive any nourishment from their host the writers are 
not prepared to assert. Nathan Banks, then of the Bureau of Ento- 
mology, to whom specimens of the mites were sent and who deter- 
mined them as the hypopus stage of Rhzzoglyphus phylloxerae Riley, 
asserts that they are saprophytes, feeding upon decaying vegetable 
matter. Whatever may be the normal feeding habits of the mites, 
it is the experience of the writers as well as of other investigators 
(Davis, 5; Smyth, 72) that the presence of these and other mites is 
highly detrimental to the grubs and also to the pupe. Upon adults 
they appear to have little. effect. The junior writer has observed 
adults almost literally encrusted with mites and apparently none the 
worse for the presence of their uninvited guests. Larve and pup 
are more susceptible, however, and it is the opinion of the writers 
that the high mortality in the larve and pupe in the breeding cages 
and boxes was due in large measure to the mites. Larve have been 
found in the field with the mites attached to them, so that it is not 
alone in the breeding boxes that they are attacked. 
At Tappahannock in the summer of 1915 these mites were very 
numerous and troublesome, but in the following year they had all 
but disappeared. Possibly such fluctuations in the numbers of the 
mites from year-to year may be one of the factors in determining 
the rather sporadic and irregular manner in which destructive out- 
breaks of ’. rugiceps appear to occur. 
The larve and pup were found occasionally to be infested with 
minute whitish nematode worms. Usually these were observed on 
the surface, where they tended to congregate in the intersegmental 
furrows, but sometimes an identical or closely similar type of nema- 
tode could be seen, through the transparent body wall, moving about 
in the body fluid. 
There are unquestionably two species of true parasites, one of 
which, a dexiid fly, W. R. Walton determined as Megapariopsis 
opaca Coq. The maggot of this fly feeds within the body of the 
larva until it is ready to form the puparium. ‘Those reared by the 
writers bored their way out of the host shortly before changing to 
puparia. 
The other parasite was a hymenopterous insect, of which none was 
reared to the adult stage. For this reason the specific identity of 
the parasite was not determined, but it closely resembles 7%ph2a 
inornata Say, the best known probably of all the enemies of Phyllo- 
phaga as described by Davis (4, p. 15) and Smyth (12). The young 
of this parasite is a thick white maggot, which during the time it 
is feeding les in a transverse position on the dorsum of its host 
gs 
