"22 CHALCID PARASITES. 



When the insect is ready to leave the pupa case of its host, 

 it gnaws an iiTCgular hole at the anterior end and crawls 

 out. Nothing is left of the fh' pupa by this time but a 

 dark shrivelled mass. Both sexes of the chalcid are capable 

 of flight immediateh^ upon emergence. 



The sexes differ (as has been mentioned by Richard- 

 son) in the form of the abdomen which is shorter and more 

 spindle-shaped in the male, whereas that of the female has 

 a prominent projecting terminal region ; and in the shape 

 of the head, which in front ^'iew is seen to be relati^•ely 

 broader and shorter in the male. The antennae are also 

 unlike, the difference being indicated in our figs. 5 and b. 



As far as our experience goes only one chalcid develops 

 in each parasitised fly j)upa, thus from 53 pupa cases of 

 which indi\adual record was kept only 53 chalcids emerged. 

 The size of the perfect insect depends upon the size of the 

 pupa in which it developed. In one instance a pujia was 

 examined two days after oviposition had taken place, 

 six eggs and two small larvae of the chalcid being found in 

 it. Two Spalangia have occasionally been seen o\'iposit- 

 ing at the same time in one pupa. The period of time 

 elapsing during summer (December to February) between 

 the laying of the egg and the emergence of the wasp is 

 between three and Jour weeks (21 and 28 days). 



Pinkus (1913) found that in the laboratory in Texas 

 during the winter months the period varied from 71) to 109 

 days when the average mean temperature was 50^ Fahr. ; 

 but that in a situation which was considerably \\armer 

 the period was shortened to (U days ; while in parasitised 

 puparia kept out of doors during the winter the larvae 

 -developed very sIomIv and did not emerge, no doiilit over- 

 wintering in the pupae. 



Our results show that larval development is passed 

 through very rapidly under Queensland summer conditions. 

 This is a factor which renders it particularh- valuable as 

 a means for controlling the spread of noxious muscids in 

 this .State. 



