HABITS OF TWO PAJRASITES OF BLOW-FLIES. 243 



(4) Nasonia can act as an accidental secondary parasite upon 

 A. mandiccator if and when puparia containing the latter are 

 within its limited reach. 



(5) Both parasites in their hibernating stage — i. e., full-grown 

 larvae — can successfully withstand over 6 weeks at 2" C. 



(6) Alysia manducator appears to be a more important parasite 

 as a natural control for the Blow-fly than Nasonia hrevicornisy 

 which appears to be more efiective as a natural control of Diptera 

 which constantly breed in permanent refuse- and garbage-heaps, 

 and where hosts would be within crawling' distance, such as 

 primarily tlie Common House-fly, Musca domesiica. 



A CKNOWLEDGMENTS . 



To Miss Cheesman, Curator of the Insect House of the 

 Society's Gardens, Kegent's Park, the writer is indebted for 

 the original lots of material from which the parasites emerged, 

 and for her assistance in procuring additional supplies of both 

 blowflies and pai'asites. 



To Mr. J. Waterston, Natural History Museum, the writer's 

 thanks are due for identifying the parasites. Acknowledgments 

 are also due to Mr. C. Gunns, Head Laboratory Assistant at the 

 Imperial College (Zoology Dept.) for assistance iu maintaining 

 supplies of cages, breeding and feeding materials. 



References. 



1. Graham-Smith, G. S. — "Observations on the Habits and 



Parasites of Common Flies." Parasitology, June 1916. 



2. Froggatt, W. W. — Miscellaneous Publication No. 1716. 



"The Sheep Maggot-fly [Calliphora rufifacies) and its 

 Parasite." Agricultural Gazette of New South Wales, 

 Feb. 2, 1914. 



3. Marshall, Rev. T. A. — " A Monograph of British BraconidiB," 



Part V. The Transactions of the Entomological Society 

 of London, 1894. 



4. Graham-Smith, G. S. — " Further Observations on the Habits 



and Pai-asites of Common Flies." Parasitology, Oct. 1919. 



5. Gatenby, J. Bronte. — "Notes on the Bionomics, Embryo- 



logy, and Anatomy of Certain Hymenoptera Parasitica." 

 Journal of the Linnean Society, No. 224, June 30, 1919. 



6. GiRAULT, A. A., and Saunders, G. E. — " The Chalcidoid Para- 



sites of the Common House- or Typhoid- fly {Musca 

 domestica Linri.) and its Allies." Psyche, Dec. 1909 and 

 Feb. 1910. 



7. Froggatt, J. L. — "An Economic Study of Nasonia hrevi- 



cornis, a Hymenopterous Parasite of Muscid Diptera." 

 Bull. Ent. Research, March 1919. 



8. Froggatt (1915).— Extracted by Graham-Smith, G. S. (1). 



9. Waterston, J. — "Notes on the Morphology of Chalcidoidea 



bi'ed from Calliphora." Parasitology, vol, ix. No. 2 

 Feb. 26, 1917. 

 Proc. ZooL. Soc— 1920, No. XVIL 17 



