Inxects. 9551 



days ; those of the autumn brood probably only reach this stage by 

 the spring, thus after an interval of seven months. The pupa repre- 

 sented at fig. 6, enlarged 2l linear, is very pale yellowish green, with 

 dark eyes, a little green coloration being observable on the prothorax, 

 the margins of the abdominal rings and the last segment; the black 

 and brown mass attached to this latter in the figure is the old larval 

 skin. This pupa remained in that state for a very short time; a couple 

 of days after the imago appeared. This was seven millimetres long, 

 expanding to sixteen millimetres, thus being somewhat smaller than 

 Nematus Salicis ; it has otherwise so much resemblance to that species 

 that it requires careful examination to separate the two. It will not 

 be necessary to describe the imago in detail ; but it will be, I think, 

 suflScient if I state the points of difference between N. Wttewaalli and 

 N. Salicis. 



Nematus Wttewaalli is, as has been said, generally smaller, its 

 largest examples resembling the smallest of N. Salicis. The antennge 

 of N. Wttewaalli are more fuscous, the head is darker, especially on 

 the vertex. The wings have a redder, less yellow, tint; the stigma is 

 brown, instead of black. The colour of both thorax and abdomen is a 

 darker orange and not so much of a gamboge-yellow. The cenchri 

 are entirely surrounded by black colouring, which colouring, moreover, 

 extends to the second abdominal segment (fig. 7). Lastly, on the 

 prothorax, near the coxae of the first pair of legs, is a small black spot 

 (fig. 8 a), and the mesothorax or breast, between the first and second 

 pair of legs, was entirely black (fig. 8 b). In fact, the points of 

 difference are greater than a cursory examination would have led one 

 to suppose. 



I obtained from this species four examples of Tryphon exstirpatorius, 

 Grav. 



I am acquainted with another species of Nematus, which, in the 

 larva state, has a very strong resemblance to N. Wttewaalli, but is of 

 a grayish green colour, and lives on poplars. The imago has a black 

 stripe over the abdomen. For want of a good specimen for drawing, 

 and from which to write the description of the imago, I am unable to 

 insert it here in order to complete the group. 



Nematus trimaculatus. 



For the larva, see De Geer, 'Memoires,' Vol. ii. p. 264, No. 17, 

 plate 38, fig. 1. 



Nematus fulvus, antennis supra fuscis, maculis tribus in thoracis 

 dorso nigris, abdomine immaculato. 



