25, e, made of white, silken threads, on the under side
of a cabbage leaf. The pupa, Fig. 25, d, and i, the end of a pupa, is
commonly white, sometimes shaded with reddish brown, and can be
distinctly seen through the silken case.
The first brood is more injurious than the second, as it feeds on the
young cabbage leaves before the head is formed, and this must surely
stunt the growth and make weak, sickly plants; while the second brood
feeds only on the outside leaves. The caterpillars are very active,
wriggling violently when disturbed, and falling by a white silken
thread.
Hot dry weather is favorable to them and enables them to multiply
rapidly. Advantage has been taken of this fact, and spraying the
plants thoroughly with water is strongly recommended. Prof. Riley
states that the insects are very readily destroyed by pyrethrum. There
are two species of spiders and a species of ichneumon fly that destroy
them.
THE GARTERED PLUME MOTH.
_Oxyptilus periscelidactylus_ (Fitch.)
The caterpillars of this species draw together the young grape leaves,
Fig. 26, a, in the spring, with fine silken threads, and feed on the
inside, thus doing much damage in proportion to their size. These
caterpillars, Fig. 26, a, and e, a segment greatly enlarged, are full
grown in about two weeks, when they are about one-fourth of an inch
long, pale green with whitish hairs arising from a transverse row of
warts on each segment.
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