Wee OO Ce ere ae 
DRE ia i ae a 
1894.] Entomology. 617 
the young are hatched. How 
long they remain within the gall 
of their parent has not been 
they escape through the opening 
in it, and seeking a healthy part 
of a leaf or more often crawling Fig. $-geoion of leaf showing gall in 
to the tenderer leaves of the new peq stage, n, n, normal leaf; o, opening 
growth,they work their way into of gall; e, eggs. (After Soraué r). 
the tissue and new galls are thus started. In this manner the galls on 
a tree are often rapidly multiplied during the summer. The mites 
live within the galls, feeding upon the plant cells, until the drying of 
the leaves in the autumn. They then leave the galls through the 
openings and migrate to the winter buds at or near the ends of the 
twigs. Here they work their way beneath the two or three outer 
scales of the buds where they remain during the winter. Fifteen or 
twenty may often be found under a single bud scale. In this position 
they are ready for business in the spring as soon as growth begins ; and 
they doubtless do get to work early for their red galls are already con- 
spicuous before the leaves get unrolled. 
" The mites instinctively migrate from the leaves as soon as the latter 
become dry. Whenever branches were brought into the insectary, as 
soon as the leaves began to dry, the mites left them and gathered in 
great numbers in the buds. It is impossible to accurately estimate the 
number of mites that may live in the galls on a single leaf. Sections 
of galls made while in their red stage would seldom cut through more 
than two or three mites; but sections of the brown galls often showed 
four or five times as many. Thus on a badly infested leaf there is 
without doubt at least a thousand of the mites." 
de. 
EET 
Fig. $i of the leaf Fiir. structure of gall in autumn; g, gall; n, 
normal leaf; o, opening of gall. 
The upper figure on the accompanying plate shows a cluster of 
infected leaves representing the brown stage of the disease as seen 
from below on three leaves and from above on one leaf; and the lower 
one shows part of an infested leaf, seen from below, with several of the 
galls considerably enlarged. 
