CONTROL OF WATTLE liAGWORM. 297 



Both Fuller and Hardenberg have recorded a secondary 

 parasite from tins fly. This is a minute chalcid, as yet 

 undetermined, metallic o-reen in colour, and measuring- two 

 millimetres in length. The adults emerge from the puparium 

 through a neat round hole whicdi they eat out of the side. 

 From one puparium, found at Mountain Rise, near Pieter- 

 maritzburg, 145 of these secondary parasites were reared, 

 IIT males and 28 females. 



Hardenberg states that the percentage of ilies found 

 parasitised by these little w^asps is small, and its effect in 

 reducing their numbers is negligible. But this does not agree 

 with my observations. Out of 87 puparia found in bags 

 collected at Mountain Rise in April last, 54, or 62 per cent., 

 were found to have been destroyed by this chalcid. 



d 



13 





15. 



Fig. 12. — CarccUa evolans, Wied. Egg. 



Fig. 13. — Carcelia evolans, Wied. Stigma, showing slit-like orifices. 



Fig. 14. — Carcelia evolans, Wied. Buccal armature of larva. 



Fig. 15. — Carcelia cvclans, Wied. Larval setae. 

 Fig. 1(3. — Carcelia evokin.s, Wied. Profile of head of adult. 



In examining bags to determine the percentage of parasi- 

 tism it is fairly easy to distinguish individuals that have been 

 killed by a Hymenopteron from those destroyed by a Dipteron, 

 even though the adult parasites have emerged and flown. The 

 empty pupal skin of the ichneumon can generally be found 

 beside the shrivelled remains of the host, and there is often a 

 small, round hole bitten in the lower side of the bag* through 

 which the adult has emerged. In the case of tachinid parasi- 

 tism, the empty puparium is left behind in the bag". Of course, 

 where immature stages of the parasites are present, there is 

 no difficulty in determining their identity. In the figures 



