262 JOHN L. FROGGATT. 



important point. It is already known that the life-cycle is 11 to 14 days under normal 

 conditions. This allows about 8 days from the date of despatch before they hatch 

 out. Therefore the length of time that the wasps will live, after emerging from 

 the pupae, in a closed space (1) without food, (2) with food, become important 

 factors. 



(1) As the work of breeding the parasite for distribution will always be more or 

 less localised in centres, from which the parasitised pupae will be sent out, a greater 

 or less time will be occupied in transit of each packet of pupae to its destination, 

 possibly resulting in some cases in the wasps hatching out before completing their 

 journey. In order to determine how long the wasps could live in a confined space 

 without food, a number of parasitised pupae were placed in glass cylinders, the tops 

 of which were covered with muslin. The dates of first emergence and of first deaths 

 were noted, as also the dates when the greatest number of the wasps had hatched 

 out and of the last deaths. This is not strictly identical with the conditions in which 

 the parasitised pupae are sent out, but it at least gives some idea of an answer to this 

 point of investigation. Under these conditions the wasps were found to five from 

 4 to 6 days. 



(2) This is important, owing to the fact that the pastoralists, to whom parasites 

 are sent, are directed to feed the wasps for some days in bottles if no suitable carcase 

 is available on the emergence of the wasps from the pupae. To investigate this point, 

 a number of parasitised pupae were placed in glass cylinders similar to those used 

 above, the tops of the cylinders being covered with muslin. As soon as the wasps 

 emerged, the muslin coverings were damped with honey and water as required. The 

 dates of first emergence, maximum number of parasites bred out, and of first and 

 last deaths were noted. The life of the wasps under these conditions was found 

 to be from 18 to 20 days. 



When kept actively parasitising in the breeding cages, the wasps five and work 

 for from 4 to 6 weeks, living longer in the cooler weather. The difference in the length 

 of the life of the wasps kept in a. confined space, and of those actively at work in 

 the cages may be due partly to the direct effects of confinement ; but in the writer's 

 opinion, it is due more to overcopulation of the females in the confined spaces. 



The imago and life-history of this wasp have been previously described by Girault & 

 Saunders (Psyche, Dec. 1909), and again by W. W. Froggatt and T. McCarthy, in the 

 Agricultural Gazette of N.S.W., and re-published in Farmer's Bulletin No. 95 (Dept. 

 of Agriculture N.S.W.), so that no further account is necessary here. 



In conclusion, it might be pointed out that it is seldom that such a hardy and 

 easily bred parasite as Nasonia brevicornis has been found. As has been shown in 

 these notes, given a plentiful supply of fly pupae, unlimited numbers of these little 

 parasites can be artificially bred and distributed. As they remain in the pupae 

 a considerable time, they can be despatched long distances without very much danger 

 of premature emergence, and with ordinary care they can be fed and kept for days 

 before liberation ; also while actively parasitising in captivity, they will live for 

 weeks. It is therefore reasonable to expect that this parasite should prove a very 

 important factor in the control and reduction of blowflies and even other species 

 of Diptera. 



