129 



Mr. R. C. L. Perkins ou Lanai, and described in the Fauna as 

 new. ]\Ir. Terry kindly bronght my attention to these para- 

 sites and offered to cooperate with me in whatever experiments 

 I might choose to undertake, and my thanks are due him for 

 assistance in this work. The two questions that presented 

 themselves at this stage of the work, were (1) whether either 

 of these parasites attacks horn fly {Haematobia serrata, R. D.) 

 pupae, and if so (2), whether they occur on all these Islands; 

 if not, they should be bred and distributed. 



To determine the first point horn fly pupae were collected 

 and placed in tubes containing active fecundated females of 

 ;Sf. hlrta (the other species had died out) and watched carefully. 

 The horn fly pupae v/ere attacked promptly and stung repeat- 

 edly, although the parasites were originally bred from pupae 

 of the stable fly {k^toDio.ri/s calcitrans, Linn.). In about 

 three or four weeks the parasites issued successfully from 

 these pupae, thus demonstrating the possible usefulness of the 

 parasite. Subsequent field study corroborated the laboratory 

 work. AVhile searching for horn fly pupae at a Palolo dairy one 

 of the parasitic flies was observed walking about within the 

 dung heap. It was captured and its identity with the survivoi's 

 from the Volcano House established. It was also ])red from 

 pupae collected in that dairy. Horn fly pupae collected at 

 Leilehua, Oahu, on August 1, 1905, were also found to be in- 

 habited by *S'. liirta. Further examination disclosed that N. 

 laiiaiviisis, the supposed native species, Avas bred from Dipter- 

 ous pupae collected in Honolulu sometime last April. These 

 facts demonstrated conclusively that these parasitic flies at- 

 tack horn fly. The distribution and effectiveness of the \)iirn- 

 sites remained to be determined. In order to gain this informa- 

 tion it was necessary to enlist the assistance of the ranch man- 

 agers. After consulting the Secretary of the Stock Breed- 

 ers' Association, a circular was sent out to all the i-anch man- 

 agers. Following is a copy of that letter: 



LETTEE TO RANCH MAXAGEES. 



* Honolulu. October 22, 1905. 



Dear Sir : — In our studies of the horn fly we have bred a 

 parasite from its pupae collected on fonr ranches upon these 



