The More Important Apple Insects. 37 
\ 
by side in clusters of 100 to 400 upon apple twigs, as shown in figure 64, resemble 
tiny flowerpots. When full grown the larva is about 1 inch in length, slen- 
der, with three pairs of prolegs, which serve readily to distinguish it from 
the spring cankerworm, which has only two pairs. The larve (fig. 65) are 
usually dark greenish or blackish in color, the majority showing on each side 
a prominent, longitudinal stripe of light lemon yellow. Like the moth of the 
spring form, females of this species are wingless and must crawl up the trees 
in order to deposit eggs on the twigs (fig. 66). The female moths (fig. 67) are 
dark gray and about half an inch long. The males (fig. 68) resemble in size 
those of the spring cankerworm and have about the same wing expanse, Neither 
sex, however, has the two rows of spines on the back of the abdomen, as has 
the preceding species. 
The remedial measures indicated for the control of the spring cankerworm 
will be effective in combating the fall form. If bands of sticky material or 
cotton (see pp. 84-85) are used,ahey should be applied in October and kept in good 
order by frequent examination until the danger of injury is over in the spring. 
APPLE-TREE TENT CATERPILLAR.” 
The apple-tree tent caterpillar constructs the unsightly tents or webs, familiar 
objects in the spring in neglected orchards and in trees along fences, roadways, 
streams, ete. During caterpillar years considerable damage frequently results 
from defoliation to young orchards and trees not regularly sprayed. It is a 
native insect and occurs westward to the Rocky Mountains. On the Pacific 
slope it is replaced by other closely related forms. The favorite host plant of 
the tent caterpillar appears to be wild cherry, though it feeds freely upon apple, 
peach, plum, and other deciduous fruits, and upon various shade and forest trees. 
The tent caterpillam passes the winter in the egg stage. The eggs are laid on 
twigs in clusters of 300 to 400 (fig. 69), each egg mass be:ng covered with a 
waterproof material. An individual egg is somewhat thimble-shaped and is 
about one twenty-fifth of an inch in length. The eggs hatch as the apple buds 
bevin to open or somewhat earlier and the larve are ready to attack the new 
leaves as soon as they appear. Almost immediately after hatching the colony 
begins to form its silken nest or tent, usually in the crotch of the tree limbs, 
sometimes at or near the trunk*ef-the tree. As the larve grow, the tent is 
enlarged from time to time to accommodate the needs of the colony (fig. 70). 
When full grown, the caterpillars make their way to sheltered places for spin- 
ning their cocoons, in which the pupa stage is passed. The full-grown larv: 
(fig. 71) is about 2 inches long, deep black with a white stripe along the back 
and blue and white spots on each side. The caterpillars are partially covered 
with yellowish hairs. The brownish pupa (fig. 72), which measures about 
three-fourths of an inch in length, is inclosed in a silken cocoon (fig. T2), 
loosely woven on the outs:de but tightly woven within, and, when freshly made, 
is more or less covered with a yellowish powder. The moths issue during mid- 
summer and soon thereafter deposit their characteristic overwintering egg 
masses. The moths are reddish-brown, the forewings having two transverse, 
oblique, whitish stripes (fig. 73). 
Apple orchards regularly sprayed for other insects will rarely be seriously 
troubled by this insect. The arsenate of lead used in the pink cluster-bud spray 
will destroy the caterpillars before they have occasioned much damage. Whien- 
ever it is desirable to spray for the tent caterpillars alone, arsenate of lead is 
advised in water or fungicide, using the poison at the rate of 1 pound of the 
*4 Malacosoma americana Fabricius. 
