AN ECONOMIC STUDY OP NASONIA BEEVICORNIS. 259 



The separation of the pupae from the live parasites inside the 'cage prevents any 

 loss of the wasps and also prevents any unnecessary handling and knocking about ; 

 for they would otherwise have to be recaptured from off the windows. 



Feeding the parasites in the cages is effected by placing small strips of calico damped 

 with honey on the glass end and sides to which they will readily adhere. The 

 wasps feed greedily from these strips, which are damped with honey and water at 

 least once a day, and in hot weather two or three times. The strips should be removed 

 every few days and fresh ones used. The old strips can be washed and used again, 

 but they need to be boiled. 



The cages, particularly during the hotter months of the year, must be kept in as 

 cool a place as possible and must never be shut out of a free current of air. Moreover, 

 they should be placed in a bright situation, the wasps working much better when the 

 cages are in a good light. 



The parasitised pupae are always held for a few days before being distributed, 

 in order to make certain that no flies will develop from the material ; as a rule not 

 ^ per cent, of flies breed out from pupae put through the breeding cage. The pupae 

 to be kept for cage breeding work are then placed in jars and the remainder distributed. 



About 400 parasitised pupae are placed in the cage for breeding purposes at each 

 addition ; and the approximate average number of parasites per pupa is 20, this 

 gives about 8,000 parasites per cage. 



The length of time in which the pupae to be parasitised are kept in the breeding 

 cages varies considerably with climatic conditions. A period of three days is generally 

 sufficient in warm weather, but in cool weather the time is much extended. With 

 experience it is not necessary to examine the pupae to make sure that they are 

 parasitised ; the behaviour of the five wasps themselves shows when they have 

 finished with any one lot of pupae. 



More work is entailed in breeding fly larvae, in separating them from the breeding 

 material, and in sorting out the fresh pupae. The principal source of supply is 

 from the larvae of the four species, Anastellorhina (Calliphora) augur, Pollenia stygia 

 (Calliphora villosa), Pycnosoma (Calliphora) rufifacies, Lucilia sericata, and also to a 

 lesser extent, Sarcophaga aurifrons. The larvae of Ophyra nigra and Pycnosoma 

 (Calliphora) varipes are also used in an emergency ; but it has been found that the 

 pupae of these two species are not selected for parasitism so readily by the wasps 

 as the former species. The larvae of all the first four species breed only in animal 

 material. After extensive trials liver has proved to breed the greatest number of 

 fly larvae per unit weight as compared with other portions of a carcase ; and when 

 well " blown " there is little or no waste with it ; and furthermore, the larvae are 

 always well grown. From a single bullock's liver over 14,000 larvae of Anastellorhina 

 augur and Pollenia stygia have been obtained at the Experiment Station. 



One fact that should always be borne in mind when sorting the larvae is, that 

 the " smooth " larvae (Anastellorhina augur, Pollenia stygia, Lucilia sericata) must 

 be kept in separate receptacles from the " hairy " larvae (Pycnosoma rufifacies and 

 P. varipes), and the larvae of Ophyra nigra must be kept apart from all the above, 

 for the hairy larvae will attack and devour the " smooth " larvae, and the larvae of 

 Ophyra nigra will attack all species. 



(C507) f2 



