DESCRIPTIONS OF SCALE AND INSECT. 51 
however, examination of the trees under observation always shows 
many migrating young which must have been born during the night, 
while observations at nightfall show always as many, and f requently 
. more, which have been born during the da} 7 . 
The gradual production of the young by the female has an important 
bearing on the question of remedies, and the old washes, which aimed 
at the destruction of the young as soon as they emerge from the females, 
are rendered almost valueless because, to make them effective, it is 
necessary to repeat them many times during a period of six weeks. 
Within two or three days after hatching the young larva? will have 
formed a scale which will be impervious to these weaker washes. 
The larva does not ordinarily travel far from the parent insect, and 
usually rests within a few inches of the old scale or at the first avail- 
able point. The} 7 will not, so far as observed, travel very far from 
the base of the tree, and in the potted trees none were observed to go 
more than 2 inches from the base of the trunk. 
DESCRIPTIONS OF SCALE AND INSECT. 
Scale of female. — The scale of the female is circular, very slightly 
raised centrally, and varies in diameter from 1 to 2 mm , averaging about 
1. 4 mm . rp De exuv j a j s central or nearly so. The large, well-developed 
scales are gray, excepting the central part covering the exuvia, which 
varies from pale to reddish yellow, altho in some cases dark colored. 
The scale is usually smooth exteriorly or sometimes slightly annotated, 
and the limits of the larval scale are always plainly marked. The 
natural color of the scale is frequently obscured by the presence of 
the sooty fungus (Fumago salicina). 
Scale of Quale. — The mature male scale is oblong-oval, nearly twice as 
long as wide, and averaging in length about half the diameter of the 
female scale. The position of the larval scale is marked by a nipple- 
like prominence located between the center and the anterior margin 
of the scale. The scale of the male is usually darker than that of the 
female, sometimes black, but often gray, the larval scale covering the 
exuvia very frequently light yellow, as with the female. Not uncom- 
monly the circular scale, formed prior to the first molt, is black, while 
the later additions, giving it its oblong shape, are gray. 
The scale covering of the hibernating insects in winter is black, and 
on the bark in summer also the scele covering is dark or often black- 
ened by the sooty fungus referred to. But the normal color of the 
scale of both female and male is light, and on the leaves of pear, for 
example, the male scales are often a very light buff, and present such 
a marked contrast to the winter appearance that no one would suspect 
them of belonging to the same insect. 
Egg. — The egg is never (or rarely) extruded as such by the female, 
and as it exists within the body of the mother is a mere amniotic mem- 
