﻿OF THE STATE ENTOMOLOGIST. 



23 



THE NATIVE CURRA'NT-WORM—PristiphoraffrossulariceWsilsh. 

 [Ord. Hymenoptera; Fam. Tentiiredinid^.] 



WHEREIN IT DIFFERS FROM THE IMPORTED SPECIES. 



" Like the Imported Currant-worm, this worm produces a Saw-fly, 

 which, however, belongs to a different genus, {Pristiphora)^ chiefly 

 distinguishable from the other one {Nematus) by the front wing lack- 

 ing what is technically termed the ' first submarginal cross-vein.' In 

 Eigure 9, ^, we give a magnified drawing of the female of this fly, and 



if the reader will look at this draw- 

 ing and compare it with that of the 

 Imported Currant-worm Fly (Fig. 

 6, a and J), he will see that there is 

 in each of them but one cell, or 

 'pane' as it might be termed, on 

 the upper edge of the front wing 

 towards its tip. This is technically 



Native Currant-wokm: — a, larva, nat. size: h, ^ ii„/i t<-K„ v^-, r> ^ r,; r. r. 1 //-.». T.orIi'o1\ 



fly, enlarged. Called the marginal (or radial; 



cell.' Now let the reader look a second time at these two figures, and 

 he will see that, underneath this 'marginal cell' there is a tier of four 

 cells in the one genus {Nematus) and a tier of only three cells in the 

 other genus {Pristiphora), the first or basal cross- vein being absent 

 or ' obsolete ' in the latter, so as to leave the first or basal cell extrava- 

 gantly large. These three or four cells, as they underlie the ' mar- 

 ginal cell,' are technically known as 'the submarginal (or cubital) 

 cells ;' and upon the difference in the number and arrangement of 

 these marginal and submarginal cells depends to a considerable 

 extent the generic classification of the Saw-flies. For example, in 

 another genus {Euura)^ which is closely allied to the two of which 

 we present drawings, there are, as in the second of these two, one mar- 

 .ginal and three submarginal cells ; but here it is the second, not the 

 Arst (or basal) submarginal cross-vein that is obsolete; so that here 

 it is the second-, not the iir&t (or basal) submarginal cell that is 

 extravagantly large, being formed in this last case by throwing the 

 typical second and third cells into one, and in the other case by throw- 

 ing the typical first and second cells into one, just as by removing the 

 folding doors two rooms are thrown into one. 



"Fersons who are not familiar with this subject are apt to suppose, 

 that the pattern of the curious network on every fly's wing varies 

 indefinitely in different individuals belonging to the same species, 



