258 JOHN L. FROGGATT. 



The economic value of this parasite has proved to be so great, where found actively 

 at work in the field, that a more extensive means of artificially propagating the wasps 

 on a large scale — by laboratory breeding and subsequent distribution — has been 

 undertaken. This work has now assumed large proportions and is still extending. 

 Under present arrangements, fifty thousand fresh pupae can be parasitised per week. 

 Some idea of the extent of the work may be gathered from the following facts : — ' 



Between November 1917 and 14th February 1918, 164 packets of parasitised 

 pupae, averaging approximately 10,000 parasites per packet, have been distributed ; 

 while fully as many have been liberated (i.e., approximately 1,500,000 five parasites) 

 on Kooroogama Station, Moree. Large numbers of parasitised pupae have also 

 been held back for work in the breeding cages. Over 200 fresh requests from 

 all parte of Australia are now waiting to be fulfilled and other requests are being 

 received daily. 



In view of the importance of this work from an economic point of view, an account 

 of the operations, with a few notes on the habits of the wasp observed in both the 

 field and laboratory, are herewith recorded. 



The work of breeding the parasites is completely carried out in cages 12 inches 

 long, 12 inches high and 8| inches wide. The bottom and one side of the cage are 

 made of wood, the other side and one end of glass, while the top and the other end 

 are covered with very fine mesh copper gauze ; the door occupies the whole wire 

 gauze end and is hinged to open outwards. Around the door, inside the cage, a light 

 beading is fixed, and so prevents the tiny wasps from escaping through any crack 

 between the door and the cage. If the beading is not present, paper must be pasted 

 round the door. Any cracks or spaces must, of course, be also pasted over. 



A tray of one-tenth inch mesh wire gauze is placed in the bottom of the cage ; and, 

 on this, a fight paper tray is placed, upon which the unparasitised pupae are spread. 

 The wire gauze tray should be made of such a size as to admit of its easy removal 

 from the cage. From a tack driven into the upper part of the wooden side, a bag 

 of mosquito net containing parasitised pupae, from which the wasps are just emerging, 

 is suspended. Through the mosquito netting the wasps escape into the cage and 

 find the unparasitised pupae. 



When the freshly parasitised pupae are ready to be removed from the cage, they 

 are tilted from the paper into the wire gauze tray, upon which they are gently rolled 

 in order to shake all the live wasps into the bottom of the cage, this being done wholly 

 inside the cage. The tray is then removed from the cage and the parasitised pupae 

 set aside, after which the wire gauze and paper trays are replaced in the cage and 

 fresh pupae added. The freshly parasitised pupae, when removed from the breeding 

 cage, are placed in shallow trays for 2 or 3 days to allow them to dry before being 

 either placed in jars or distributed. If placed in jars immediately, the moisture given 

 off is sufficient to saturate them with the accumulated water and so to kill the 

 immature wasps within the pupal shell. 



The whole of the operation of transferring and changing the pupae should be done 

 in front of a window and with the glass end of the cage placed towards the light. 

 The wasps are strongly attracted to light and so will make toward the end of the cage 

 farthest from the door, thus obviating any loss of parasites. 



