276 THK p:NTOMOLOGISr. 



pi. 65, fig. 3), do not apply to the perfect insect, which in 

 this instance I have reared. The species of insect reared by 

 Redi and Reaumur from willow-galls is uncertain, and it is 

 equally so witli regard to the species of Nematus, meant by 

 Linnaeus under the name of Tenthreclo Galloe foliorum 

 Salicis, and by Fallen and Dahlbom under that of Nematus 

 Saliceti. Taking all this into consideration I thought it 

 best to give my species a distinct name, in order to avoid all 

 confusion for the future. It is quite clear that there are two 

 species living entirely in the same manner within galls on 

 willow leaves, one of which species was reared by Swam- 

 merdam, and perhaps by all the other above-named authors, 

 at all events up to the lime of the insect leaving the gall ; the 

 other species being the one I am now describing. All the 

 published descriptions of the gall agree with what 1 have 

 myself observed : this may also be said of the larva, if its 

 more or less green, or gray, or yellow colour is left out of 

 consideration. I cannot say much with certainty respecting 

 the pupa, but in this slate the Hymenoptera offer few or no 

 specific characteristics, especially in the case of such nearly- 

 allied species as Saliceti, Vallisnerii, and Lugduiiensis. 

 The imagos, however, differ greatly in colour, especially the 

 females ; and I regard the entirely yellow stigma in that sex 

 as a special characteristic of my species. 



I shall endeavour to describe and figure the other species, 

 which, also, according to Swammerdam, occurs in this 

 country, and has been met with by Messieurs Snellen and 

 Wttewaal. 



I am not acquainted with the egg; most probably it is like 

 that observed by Swammerdam, of an elliptical shape and 

 semi- transparent. 



I found the galls on our common white willow {Salix alba) 

 and on the red willow [Salix purpurea). They were perfectly 

 alike, projecting on either side of the leaf, smooth, shining, 

 and of a red colour; that on the red willow, however, being 

 generally somewhat larger. When young they are more 

 filled up inside than later, when the parenchyma is almost 

 entirely eaten out by the larva. The gall itself is nothing 

 but a diseased swelling out of the parenchyma of the leaf. 

 1 must here especially call attention to the fact that the 

 imagos reared by me all came from galls of Sali.v purpurea. 



