The Green Tortrix (_Tortrix viridana_) has wings of a green colour, with the margin and fringe whitish on the anterior, and of an ashy grey on the posterior wings. The under-side of the four wings is of a bright white, as if it had been silvered. This pretty moth comes out in the month of May. It is so common everywhere, that at this season it is only necessary to shake the branches of the oaks which border the alleys of the woods to set in motion hundreds of them. The caterpillar is green, with black warty spots, each having a hair of the same colour. They are wonderfully lively, the moment they are disturbed taking refuge in a rolled leaf, which serves them as a dwelling-place. If they are pursued, they let themselves fall by the aid of a thread, and do not re-ascend till they think they can count on repose and security. This, and many kindred species, do a great deal of damage to our trees. They strip them of their leaves, and sometimes give them, during the first days of summer, the sad and melancholy appearance which they present in the middle of winter. [Illustration: Fig. 275.--Antithesia salicana.] [Illustration: Fig. 276.--Poedisca occultana.] [Illustration: Fig. 277.--Argyrolepia æneana.] [Illustration: Fig. 278.--Sericoris Zinkenana.] [Illustration: Fig. 279.--Sarrothripa revayana.] [Illustration: Fig. 280.--Cochylis francilana.] [Illustration: Fig. 281.--Choreutes dolosana.] We have just alluded to the tube formed of a rolled leaf, in which the caterpillar takes refuge, and in which it lives. This tube it constructs itself. Réaumur has devoted a magnificent chapter of his Memoirs to observations on the skill with which divers species of caterpillars fold, roll, and bind the leaves of plants and trees, especially those of the oak. Let us listen to the great observer:--"If one looks attentively at the leaves of the oak tree towards the middle of the spring, many of them will be seen to be rolled in different ways. The exterior surface of the end of one of these leaves has, it appears, been rolled back towards the interior surface, in order to describe the first turn of a spiral, which is then covered by many other turns (Fig. 282). Some leaves are rolled towards their exterior surfaces, others are rolled towards their interior surfaces, but in a totally different direction. The length or axis of the first roll is perpendicular to the principal rib and to the stalk of the leaf, the axis of the latter parallel to the same rib (Fig. 283). Work of this kind would not be very difficult to perform for those who had fingers; but caterpillars have neither fingers nor anything equivalent to fingers. Moreover, to have rolled the leaves is only to have done half the work: they must be retained in a position from which their natural spring tends constantly to draw them. The mechanism to which the caterpillars have recourse for this second part of their work is easily perceived. We see packets of threads attached by one end to the