158 
Psyche 
[June- August 
great variety of insects, that a complete list would be very 
difficult to give. It occurs most abundantly, however, in con- 
nection with cereal insects such as, Sitotroga cerealella Oliv., 
Sitophylus granarius, Linn., S. oryza Linn., and notably, Isosoma 
species, all of which are greatly checked. It also feeds upon the 
parasites of these and of other insects and would, probably, 
feed upon any insect that was unable to escape. Because it 
controls the depredations of many destructive insects, Pedicu - 
hides has been considered beneficial from an economic stand- 
point. 
In contrast to this view, the mite has been considered nox- 
ious, principally, because it causes a disagreeable, eruptive derma- 
titis, which is accompanied by a severe itching. If enough 
lesions are made, the person afflicted will have other symptoms, 
such as a rise in temperature, an acceleration of the heart rate, 
intense headache, anorexia, nausea, and diarrhoea. Such cases 
occur in the harvest fields of the Middle West, and in grain 
elevators, warehouses, and farm homes that have fresh straw 
mattresses. Here the mite is associated, of course, with the 
cereal insects mentioned. 
In my opinion, Pediculoides is noxious to a degree as yet 
not realized, for another reason, and that is, its destruction of 
parasites. It has been widely observed that parasites of a great 
variety of insects are attacked by this predaceous mite, but it 
appears that these facts have not been stressed. Parasites reared 
in cultures in the laboratory are very commonly completely des- 
troyed. Lichtenstein in France in 1863 stated that he could not 
for six months, breed a single specimen of Hymenoptera, while 
Buprestids, Cerambycids, and some Lepidoptera were also com- 
pletely destroyed. Berlese cites the fact that Newport was forced 
to abandon the rearing of hymenopterous larvae, while Essig 
mentions that in the rearing of hymenopterous parasites for the 
control of scale insects in California, the mite not only destroyed 
all the parasites in some insectaries, but also attacked the at- 
tendants. 
My own experience follows: — The prepupae of Eurytoma 
pissodis Gir., a hymenopterous parasite of the white pine weevil, 
Pissodes strobi Peck, were dissected out of the larval chambers 
