( 571 ^ 



XVII. NotcE Dipterologicce. No. 4. — Blonograph of the 

 genns Systropus, xoith notes on the economy of a 

 new species of that genus. By J. O. Westwood, 

 M.A., F.L.S., Pies. Ent. Soc, &c. 



[Read 6th September, 1876.] 



In a collection of insects sent from Natal by Herr 

 Gueinzius were several specimens of a new species of 

 the remarkable Dipterous genus Systropus, together with 

 several cocoons and their contents found upon a tree of 

 the genus Mimosa, from one of which one of the Systropi 

 had been bred. The perfect insect itself is described 

 below, under the name of S. crudelis. 



The cocoons are of an oval form, except that on one 

 side they are flattened, shoAving marks of having on that 

 side been attached to the bark of a branch or stem of the 

 tree. At one end is a circular piece which is easily dis- 

 engaged, the insect making its escape through the orifice 

 formed by its removal. This cocoon is 7 lines long. The 

 outer surface is quite smooth but not shining ; the inner 

 surface is also smooth and glossy, having its upper end of 

 a darker colour than the remainder of the interior. In the 

 absence of direct information we can only conjecture that 

 the cocoon is that of a species of Egger moth (as certain 

 British species are termed from the egg-like cocoon formed 

 by their caterpillars), whilst the thick, parchment-like 

 covering and shape of the cocoon agrees with those of the 

 stinging larvje of the genera Limacodes or Doratifera. 



Within each of these cocoons Avas found the pupa 

 represented, magnified in the accompanying figures 6, 7 

 and 8, of a short and thickened form, and quite unlike the 

 parasitical pupas of Anthrax or Bombylius. The head- 

 piece is armed with a strong, conical, frontal projection, 

 by means of which the pupa is doubtless enabled to push 

 off the operculum at the end of the cocoon. The head on 

 the underside is furnished with a long appendage, extend- 

 ing along the breast as far as the first ventral segment; its 

 basal half is grooved down the centre as though it consisted 

 of two halves ; these are probably the antennjE cases : the 

 remainder of the appendage seems jointed in the middle. 



TRAN8. ENT. SOC. 1876. — PART TV. (dEC.) V T 2 



