This insect has a flat yellow body and four pellucid wings, the two outer ones marked with brown on the edge. In April it issues from the pupa, which has lain under ground from the preceding September. The female of the gooseberry saw-fly does not, like some of the family, cut a groove in the branch to deposit her eggs;--"of what use, then," asks Réaumur, "is her ovipositor-saw?" In order to satisfy himself on this point, he introduced a pair of the flies under a bell-glass along with a branch bent from a red-currant bush, that he might watch the process. The female immediately perambulated the leaves in search of a place suited to her purpose, and passing under a leaf began to lay, depositing six eggs within a quarter of an hour. Each time she placed herself as if she wished to cut into the leaf with her saw; but, upon taking out the leaf, the eggs appeared rather projecting than lodged in its substance. The caterpillars are hatched in two or three weeks; and they feed in company till after midsummer, frequently stripping both the leaves and fruit of an extensive plantation. The caterpillar has six legs and sixteen pro-legs, and is of a green colour mixed with yellow, and covered with minute black dots raised like shagreen. In its last skin it loses the black dots and becomes smooth and yellowish white. The Caledonian Horticultural Society have published a number of plans for destroying these caterpillars. [Another remarkable mode of disposing of the pupa is shown in the accompanying illustration; it represents the nest of an exotic saw-fly, named _Deilocenes Ellisii_. In this instance, the numerous larvæ unite in spinning for themselves a common envelope of considerable strength; it is seen as it appears when attached to the branch of a tree. The material of which it is composed is the tough silken fibre spun by the larvæ of so many insects, which may be seen in perfection in the cocoons of the Microgaster. Two species of this curious group will be described in a future page. By the side of the branch is seen a diagram of the same nest, as it would appear in section. The irregularly angular cells are seen in the centre, and around them is the common envelope composed of fibres. As may be seen from the upper figure, as soon as the insects have attained their perfect form, they gnaw their way out of the cell and the covering also. The insect is shown as it appears when flying. [Illustration] We will conclude this chapter by a few remarks upon some exotic insects, whose nests are not only remarkable in their form, but are valuable to the entomologist in affording grounds for the reception or rejection of certain familiar theories upon the subject of this volume--Insect Architecture. Several of these nests are of comparatively late discovery, and are therefore found in this work.