8 1 78 Insects. 



lets itself fall to the ground, and, after having crawled about for some 

 time, spins itself an oval cocoon, covered on the outside with little 

 grains of earth, being black and smooth on the inside. The larva 

 generally remains one year in the cocoon before changing to the 

 pupa ; some individuals, however, assume the pupa state within eight 

 months, and emerge in May. From this we should be led to suppose 

 there are two generations in the year ; however, I have never found 

 the larva earlier than August, and find no record of larvae in May and 

 June. The pupa is represented at fig. 5. The imago gnaws its way 

 out by an oblique irregular opening in the cocoon. 



The National Museum of Natural History has two specimens of the 

 female, from my collection, both of which have only three submarginal 

 cells in the right fore wing, the second submarginal being united to 

 the third, in consequence of the absence of the middle transverse 

 iiervure. Nematus latipes, described as a distinct species by Foul- 

 ques de Villaret in the 'Annales de la Societe Entomologique de 

 France,' is only a variety of this species. Probably his Nematus 

 varus and N. laticrus are also only varieties of N. septentrionalis. 

 We must, however, not omit to mention that Ratzeburg considers 

 Nematus varus to be distinct, for the two following reasons : — first, 

 there is a difference between the iraagos, not only in colour but also 

 in structure ; for example, in the form of the hinder tibiae, which are 

 not so suddenly nor so much expanded towards the end : and 

 secondly, there is a great difference in the colour of the larva, which 

 appears to want the orange tinge, and seems to be entirely green, 

 with black spots on the sides. He also includes the sawfly described 

 by DeGeer ; but in this he is certainly in error, for DeGeer distinctly 

 states that his larvae had the first and last segments of the body yel- 

 low, inclining to orange. So far as we know there seems to be 

 no reason why we should not regard the four species as one.* 



I have not reared any parasitic wasps from the larvae of this species. 

 Ratzeburg, in his * Ichneumonen der Forst-Insecten,' records no less 

 than nine species of Ichneumonidaj and Braconidae, which were 

 reared in Germany from Nematus septentrionalis. 



* Since the above was published in the original, the following has been received 

 from the author: — 



" I have lately discovered that Ratzeburg was quite right in his assertion that 

 Nematus varus is a distinct species. I have reared this latter insect from the larva, 

 which is in fact entirely green, with black spots." 



