10 DEPARTMENT BULLETIN 1267, U. S. DEPT. OF AGRICULTURE 
larvee are often infested with certain mites, which are decidedly in- 
jurious to them and frequently cause their death. During the season 
of 1915 these mites were so abundant and widely distributed that it 
was found necessary to fumigate all samples of soil used in the breed- 
ing boxes. 
The salve-box method of rearing larve recommended by Davis 
(5, p. 138) gave the best results and proved entirely satisfactory, 
once the peculiar needs of the young larve were ascertained. The 
principal difficulties were to provide them with an adequate supply 
of suitable food and to protect them from mites and disease fungi. 
A few grains of wheat or corn were added to the boxes containing 
the young larve, but the larve made no attempt to feed upon either 
the grain itself or the plantlet issuing from it. Scarcely better 
results attended the use of the different kinds of manure, either 
fresh or old and thoroughly weathered. The fine, fibrous rootlets 
of the corn plant were also tried, but without success. Finally, a 
satisfactory food was found in a well disintegrated, brownish plant 
residuum, or vegetable mold, a thin layer of which occurred fre- 
quently in an old pasture at Tappahannock, where the'species bred 
abundantly. At first this material was gathered beneath tussocks of 
the common rush (Juncus effusus) where it consisted of the broken 
and decayed culms of-this plant, but subsequently was obtained 
with much less difficulty in connection with certain grasses belonging 
to the genus Paspalum and with Japan clover. It was the original 
intention to utilize this material, owing to its softness, merely as a 
medium in which the young and tender larve might be kept with 
the least chance of suffering injury. At first a grain or two of wheat 
was added to each of the boxes containing this material, but it was 
soon noticed that the wheat was left untouched, whereas the vegetable 
mold decreased rapidly in amount as the larve grew and was e- 
placed by excrement. The wheat kernels were thereafter omitted 
and finely sifted vegetable mold alone used with entire success. 
A larva, after emerging from the egg, was carefully removed to a 
small tin salve box previously half filled with a quantity of the vege- 
table mold, finely sifted and slightly moistened. The young larva 
would invariably burrow into the mold and excavate for itself an 
irregular cavity, or cell, and there feed upon the surrounding ma- 
terial, When this had been consumed, the larva was temporarily 
removed from the box, the feces and other wastes cleaned out, and a 
fresh supply of mold added. 
As the larve grew, the amount of mold consumed by them in- 
creased rapidly, necessitating frequent replenishing. The plan was 
adopted of substituting for the vegetable mold a kernel or two of 
corn, previously softened by soaking in water overnight. With larve 
from half-grown to full-grown this proved to be a satisfactory substi- 
tute for the mold, and greatly lessened the work of caring for them. 
Fresh kernels were added only when the old ones had been almost 
consumed. 
Considerable difficulty was experienced in protecting the larve 
from the minute mites previously referred to, specimens of which 
were identified by Nathan Banks as the hypopus stage of Rhizo- 
glyphus phylloxerae Riley. During the season of 1915 this pest was 
