Tortrix
(from torqueo, to twist; in allusion to the leaves of plants being twisted or rolled by the larvae, to form tubes in which they live). The leading genus of the group of small Moths known as the Tortricina. The genera in this group are distinguished from one another by very slight characters, so that it is difficult for any one but a specialist to be sure of the genera and species. Tortrix is closely related to several other genera, and its extent is somewhat uncertain; some specialists forming several genera from an assemblage of species that others consider ought to be retained in one genus. In the genus, even when most restricted, there are several species hurtful to garden produce and to cultivated trees. Of these the most destructive is T. viridana. This insect has the fore wings pale green, with their front margin sulphur-yellow; they extend from 2/3in. to 1in. in span. The larvae live in tubes formed by rolling up leaves of almost all kinds of trees, and of some shrubs; but they are peculiarly destructive to Oaks, which they occasionally strip absolutely bare. T. icterana has pale-ochreous wings, and is about the same size as T. viridana. Its larvae feed mostly in rolled leaves of herbs, and may be looked on as almost harmless, as they usually feed on weeds. T. heparana and T. ribeana are both brown, with darker markings. The larvae of both feed on the leaves of various trees, and are at times hurtful to fruit-trees. T. (Enectra) Pilleriana, though very rare in Britain, is, in some seasons, very destructive to Vines in France, and elsewhere on the Continent, stripping off the leaves. The larvae have been observed passing the winter sheltered under loose bark, emerging in spring to feed on the buds and young leaves. The fore wings of this Moth have a spread of only about 2/3in.; they are pale ochreous, with a brown patch near the base, and a brown cross-bar in the middle. The other British species of the genus are not sufficiently hurtful to call for special mention.
Remedies. These are given under Tortricina.