133 
that they could not be traced to the outlet, but on several occasions 
I have seen the anterior ovum forced through this opening by the 
pressure of the cover-glass. 
The eggs are attached singly to the walls and 
hairs of the cecidii. They are slightly depressed, 
r~ nearly spherical, and those I have seen were light 
[yt Jes) yellow in color. Two examples of these eggs from 
Aer ; inch in di r, and 
43 the green ash measure .001 inch in diameter, an 
Figure 29.— Egg of . : ; 5 = 5 
Prgegine piadrises,s one from soft maple .CO2 inch in diameter. The 
seen attached to the In- developing mite may be seen in some of the eggs, 
ee ere sie ararie and in one of those observed by the writer, the 
(Acer dasycarpum). two pairs of legs and the abdominal strie ap- 
peared much as in adults. 
The young mite, fresh from the egg, is very helpless. Several 
molts of the skin take place before it is mature, and many of 
these molting young may be found by washing out a cecidium 
during their period of most active growth. At each molt there is 
a period of inactivity, during which: the mites lie encased in the 
loose old skin. Landois claims to have observed four molts, the 
first occurring just after the mites leave the eggs, when the tarsal 
appendage appears; at the second there is only an increase in size; 
while at the third, the first and at the fourth, the second pair of foot 
stumps appears. One of the smallest young I have seen measured 
.003 inch in length,—the adult from the same cecidium measured 
.008 inch in length. 
HABITS. 
The mites move about quite rapidly, when their size is taken into 
consideration, depending mainly upon the short legs for locomotion. 
Briosi says that they also move in the same manner as the larve of 
Phalenide, the terminal sucker playing the part of the false feet. 
I have not witnessed this movement, but can easily believe them 
able to move as he describes. The sucker seems to me to be 
used chiefly in clinging; and is doubtless of service to the mites 
in preventing the weight of the long abdomen from pulling them 
from the under side of the leaves upon which they may be 
ereeping. While watching the mites at home in a nook of a gall 
or bud, I have sometimes seen them attach themselves by the 
sucker and swing the body about into a new position. The sucker 
takes hold on whatever it touches, and the mites themselves are 
sometimes seized upon by their neighbors and dragged about by it. 
Phytopti hibernate in the perfect state during the winter, and while 
some of them may descend to the ground for that purpose, as is 
supposed by Dr. Shimer and others, all of them certainly do not 
do so; for I have been able to obtain mature and active specimens 
from twigs at any time during the winter by bringing them into a 
warm room, and at times from a temperature but little above zero, F. 
SPECIES. 
While [ am alive to the possibility that a species of Phytoptus 
may have a wide range of plant food, and produce very different 
