8 NATURAL HISTORY. 



thickened at the apex, sometimes pectinated in the males, and composed in different genera of from 

 three to thirty joints; the ligula is broad, and divided by deep notches into three parts ; the maxillary 

 palpi have six joints ; the prothorax is produced at the sides to the origin of the fore wings ; and 

 the anterior tibia? have two spurs at the apex. 



In their general habits these insects present a considerable uniformity. The females, by means of 

 their saw-like ovipositors, cut slits in the leaves or tender growing shoots of trees and plants ; the 

 two plates of the saw are then separated a little, so as to widen the aperture already made, and 

 then an egg passes down to its destination between them. The irritation produced by this process, 

 assisted, according to some entomologists, by a peculiar secretion which accompanies the egg, causes a 

 flow of sap to the wound, and the egg by contact with this quickly becomes considerably enlarged. 

 The larvre hatched from these eggs are generally very like the caterpillars of Butterflies and Moths 

 in structure and appearance ; they all possess three pairs of thoracic legs, and the great majority have, 

 in addition, from six to eight pairs of abdominal pro-legs. These, however, differ from the corresponding 

 organs in the larvae of the Lepidoptera, by being destitute of the peculiar circlet of generally 

 hooked bristles which the latter possess. The larvae of the Saw Flies also have only a single simple 

 eye on each side of the head. When full grown the larvae spin a cocoon, which is sometimes parch- 

 ment-like in its texture, sometimes lattice-like, and occasionally exhibits a combination of the two 

 characters. These cocoons are either attached to the leaves and twigs of the plants and trees on 

 which the larvae have lived, or placed underground, but in either case the larva remains unchanged 

 within its cocoon until the time for the emergence of the perfect insect approaches, when it undergoes 

 the change to the pupa state, and from this the imago is speedily produced. The number of known 

 species of the family is estimated at over a thousand, a very considerable proportion of which live 

 in Europe. Many of them are inhabitants of Britain. 



The species of the genus Lyda have long bristle-shaped antennae of numerous joints, a broad 

 head, a flat abdomen, and three spines at the apex of the second and third pairs of tibiae. Two species 

 (L. pratensis], a black insect with yellow markings on the head and thorax, and the abdomen 

 margined with rusty red, and L. campestris, which is blue-black, with the middle of the abdomen reddish, 

 and the antennae, scutellum, tibiae, tarsi, and wings yellow, both about half an inch long, live on pines 

 and firs, the larvae feeding in company under a sort of web which they spin ; another rather smaller 

 species (Lyda betulce), which is reddish-yellow, with the thorax and the base and apex of the abdo- 

 men blue-black, feeds on the birch, and is very generally distributed. Lopliyrus pini is a very 

 common species on coniferous trees. The sexes differ in colour, the male being black with yellow 

 legs, and the female yellow, with the head, three spots on the thorax, and the middle of the 



abdomen black ; the antennae in the female are serrated, in the male 

 pectinated on both sides. The insect is about a third of an inch long, 

 and, like the species of Lyda above mentioned, sometimes does con- 

 siderable damage. Nematus ventricosus, a small reddish-yellow species, 

 about a quarter of an inch long, with the breast and three spots on 

 the back of the thorax blackish, haunts gooseberry and currant bushes, 

 producing two broods in the year, and sometimes almost stripping the 



LOfHYRfS PINI. i .1. . , 



bushes or their leaves. amphylus grossidama?, is another enemy of 



the gooseberry. Athalia spinarum is a species of a reddish-yellow colour, with the head and tho 

 sides of the posterior part of the thorax black. It measures about a quarter of an inch in length. The 

 larva feeds on the leaves of the turnip and other cruciferous plants, to which it frequently does great 

 mischief. The species of Hylotoma, one of which (//. ros'intm) attacks roses, have only three joints in 

 the antennae, the last joint being longer than the others ; in those of the genus Cimbex, which are 

 among the largest in the family, the antennae have seven or eight joints and terminate in a good-sized 

 club. Tenthredo cethiops, a small black species, deposits its eggs upon fruit-trees, showing a preference 

 for cherry-trees. Its larva is black, and often occurs ill such abundance as to damage the trees. The 

 larvae of certain small species mine the leaves of the plants on which they feed ; while the irritation 

 caused by the presence of others produces small excrescences or galls within which they live. A 

 common example of this last habit is the little Nemattfs saliceti, the larva? of which reside in small 

 protuberances of the leaves of several species of willows. 



