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Web-Forming Caterpillars

Almost all the Caterpillars of Butterflies, Moths, and Sawflies can and spin silken threads when required; but many of them hardly do so except to form a cocoon, for the protection of the pupae; while many do not even spin a cocoon. Many larvae spin together several leaves to form a protection for themselves against birds or other foes, or they draw a leaf into a tubular form, with the same object, keeping it in position by silken threads. The Web-formers are not very numerous, though they belong to widely different groups of Lepidoptera. Several of them live on Hawthorn leaves, such as the Black-veined White Butterfly (Aporia Crataegi), the small Ermine Moths (Hyponomeuta padella, &c.), and Sawflies of the genus Lyda (e.g., L. punctata). The larvae of these insects, when young (or during their whole life as larvae), live in webs spun by a number of them in common, sometimes over a whole branch, but usually over several leaves. Some form separate silken tubes for themselves inside the webs; others are contented with the protection afforded by the web alone. An account of the several insects just mentioned is given under the heading Hawthorn Caterpillars.

The larvae of various European and exotic Moths form much more striking and conspicuous webs than do the British species--e.g., the Processionary Moth (Cnethocampa processionea), which feeds on Oaks in Germany. The larvae spin a web, on which they lie, and, when going to feed, they march in a regular procession-first one, then two, then three, and so on, those in each line moving side by side, till they reach suitable food, when they disperse and eat what they require, and thereafter return to the web in the same regular order. When full-fed, they spin a compact web, under cover of which they form their separate cocoons to protect themselves while they are pupae.

Remedies. Web-forming Caterpillars are easily got rid of by tearing down the webs, or cutting off the branches, and destroying the larvae.