156 



of 20 eggs in each pupa. Dirhinus sarcophagae [R. A.E., B, viii, 60], 

 has a hfe-cycle of 28 days in Brisbane. Spalangia mnscidariim attacks 

 house, bush and stable flies, blowflies and flesh flies. A single parasite 

 emerges in 21-28 days from each infested pupa. Several other species 

 have been recorded from Queensland, but their habits are not known. 

 Chalcis calliphorae [R-ATe., B., iv, 179] attacks the maggot stage, 

 but has only once been recorded in Brisbane. An Encyrtid discovered 

 last year attacks the maggots, which are destroyed after pupation, 

 the adult parasites emerging in 21-23 days. It is being bred now in 

 the Laboratory and should be tried in conjunction with Nasonia and 

 Spalangia. Hemilexomyia ahnipta has been found occasionally in 

 New South Wales, but' has not yet been recorded in Queensland. 

 Diapriid parasites related to, but distinct from, the latter have been 

 bred on one occasion from blowfly pupae. Pachycrcpoideiis diibius 

 has been recorded from North Queensland as destroying house-flies, 

 but its effect on blowflies is not known. 



Unsuccessful attempts (as it was mid-winter) were made to obtain 

 from England pupae parasitised by Alysia manducator, which oviposits 

 in blowfly larvae, the adult emerging from the pupa. The accessibiUty 

 of pupae to pupal parasites is a very important factor. Experiments 

 prove that only 4 per cent, of the larvae pupate on the surface of the 

 soil. Owing to the wandering habits of the larvae, the parasites that 

 attack this stage have more opportunity of infesting them. 



The Blowfly Pest. — Queensland Agric. Jl., Brisbane, xx, pt. 6, June 

 1921, pp. 249-253, 2 plates. 



The work of the Special Blowfly Committee, appointed by the 

 Commonwealth Institute of Science and Industry, was extended at 

 Dalmally in February 1918, with a view to checking blowfly ravages 

 in flocks. A flock of 14,000 was treated. The apparatus employed 

 included a power dip and spray and jetting plant. The work and life- 

 history of the Chalcid [Nasonia brevicornis] was also closely studied. 



The various applications used in the experiments are given. Soap 

 and water solution failed and the fly-trap method was not satisfactory. 



Mr. W. A. Russell found from measures taken on his property 

 that the jetting process checks fly attacks immediately, prevents 

 losses, and for a time arrests further infestation. This process con- 

 sists in forcing a mixture of arsenic and sheep dip through a mechani- 

 cally operated nozzle at a pressure of 100 to 120 lb. Only the breech 

 of the sheep is treated, and it is possible for one man to treat over 

 1,000 sheep a day in this way. Complete immunity may be secured 

 for three or four months, though virulent attacks abate after a few 

 weeks. So far non-poisonous specifics have proved valueless and the 

 stronger the poison the greater the protection. Arsenic and other 

 poisons are now being used in strengths that would have once been 

 thought fatal. Very httle arsenic is retained in the wool, and experi- 

 ments with a much greater strength are going to be undertaken in 

 order to fix it in the wool and so give complete immunity. Crutching 

 is not necessary when jetting is done. Every remedy suggesting reason- 

 able chances of success has been experimented with. An arsenical 

 and oil mixture was tried with success, the arsenic being held in sus- 

 pension, but this was a more expensive process. Mr. Russell attributes 

 the failure of jetting in some cases to the use of an inferior grade of 

 arsenic, and to its not being properly dissolved. He uses specifics 

 mixed with arsenic up to 101b. to 100 gals., but does not recommend 

 this strength for general use. 



