The More Important Apple Insects. 65 
OYSTER-SHELL SCALE.” 
The oyster-shell scale is of common occurrence, and because of its character- 
istic appearance (fig. 130) is readily identified by orchardists and others 
who may discover its presence on their trees. It is apparently not very 
fastidious, being found on a great variety of fruit and shade trees, bushes, and 
shrubs. Poplar was long supposed to have been 
a favorite food plant, but it is now believed that 
the insect most commonly found on poplar is not 
the same as the apple form. Frequently the 
oyster-shell scale is found in apple orchards, and 
although it usually ranks as a scale pest next 
to the San Jose, it is seldom very destruc- 
tive. It sucks out the plant juices from the 
trees, limbs, trunks, foliage, and fruit, the prin- 
cipal injury occurring on the woody portions of 
the tree. Young trees heavily incrusted are 
sometimes killed, while older trees may occa- 
sionally be seriously injured, resulting in the Fie. 130.—Twig incrusted with 
death of twigs and limbs. On the fruit the scale ibe te csi Soe 
causes small reddish dots, somewhat similar to neat 
those produced by the San Jose scale, thereby disfiguring the fruit and render- 
ing it objectionable from the marketing standpoint. 
The winter is passed in the egg stage beneath the scale covering. The eggs 
(fig. 131), which are yellowish white, hatch in from 2 to 3 weeks after the apple 
blooms and shortly thereafter the young yellowish white scale insects settle on 
some part of the host plant. The male insects are winged, and upon reaching 
maturity during the summer mate with the females. The female scale covering 
is about one-eighth of an inch long, dark prownish gray, and resembles in general 
shape the oyster shell. The male scale covering is much smaller and is oval. 
In the North, where there is only one generation annually, egg laying takes 
place during late summer to early fall. In the more southern districts, includ- 
ing the southern parts of New Jersey and Pennsylvania, 
there are two generations yearly. 
While dormant treatment with winter-strength lime-sul- 
phur solution is not generally as effective against the 
oyster-shell scale as against the San Jose scale, orchards 
regularly sprayed for the latter will not usually be 
troubled with the oyster-shell scale. In cases of severe 
infestation the dormant spraying may be supplemented 
with a contact spray of 10 per cent kerosene emulsion 
applied when the young are hatching. 
Fie. 131, — Appear- 
ance of eggs of SCURFY SCALE.” 
oyster-shell scale. 
Enlarged. Apple and pear trees, aS well as other common deciduous 
tree and bush fruits, are frequently attacked by the 
scurfy scale, which retards the growth and vitality of its host. In severe in- 
festations this scale has been known to kill young trees, but usually injury is 
confined to a few twigs or limbs. Occasionally it settles and feeds upon the 
fruit, resulting in reddish dots somewhat larger than those caused by the San 
Jose scale. The scurfy scale (fig. 182) is native to the United States, and 
58° Lepidosaphes ulmi Linnaeus. 51 Chionaspis furfure Fitch. 
92300°—22 5 
