8790 Insects. 



description of a sawfly under the name of Tenthredo Amerinae, which, 

 however, is not Amerinae, but probably Lucorum. This has hitherto 

 caused much confusion in the descriptions of these two so nearly 

 allied Cimbices, which we hope our present paper will clear up for 

 the future. The eggs of this species are attached to the veins of the 

 leaves of the willow. The larvae emerge in June, and remain in com- 

 pany until the second moult. Their growth is slow, so that full-grown 

 larvae are met with until August, and even till late in September ; 

 these must be tjie product, if not of a second generation, at all events 

 of eggs laid later in the season. 



When full-grown the caterpillar is 3j neth. inches (centimetres) 

 long ; the first three segments are stouter than the others, and the 

 whole larva decreases gradually in size towards the tail ; it has twenty- 

 two legs, and is of a green colour, darker on the back, having more of 

 a grayish tinge towards the ventral surface. The head is green, and 

 the eyes are placed in round black spots ; the entire skin is wrinkled. 



The margins of the spiracles are black, having the form of the im- 

 pression of a stag's hoof, being hereby distinguished from those of 

 most other Cimbices. Above the spiracles are the mouths of small 

 round excretory canals, as is the case in Abia aenea, Kl. (see fig. 2). 



Each abdominal segment is divided on the dorsum into seven der- 

 mal folds, as shown in the third figure, which also gives the colour 

 characterizing the larva during the winter, which season it passes 

 in the cocoon. 



It scarcely ever makes use of its last pair of legs ; it uses the ante- 

 rior legs in crawling, and even in the act of progression curls the ter- 

 minal segments under the belly. 



During the day time it usually lies rolled up on the leaves of the 

 willow, but in the evening crawls up the tree and feeds on the leaves. 



This species also is able to defend itself from attack by ejecting a 

 clear fluid, which it can throw to a distance of more than a foot; the 

 mouths of the ducts conveying this fluid may be seen just above the 

 spiracles. If the animal is touched on the left side, the fluid is ejected 

 from that side only, and so vice versa ; but if it is touched on the 

 back it defends itself from both sides simultaneously. After having 

 performed this action five or six times, it is obliged to rest some time, 

 in order to receive a fresh supply of fluid in the ducts. This faculty 

 of ejecting a fluid is possessed most strongly after the second change 

 of skin, and is entirely lost if the larva be not kept supplied with fresh 

 leaves for food. 

 • In August or September, or, according to Hartig, as early as July, 



