HORSE-FLIES AND WESTERN AGRICULTURE. 



inches deep and 11 by 14 inches horizontally formed the base of 

 the cage. A wire frame 18 inches high fastened to the corners of 

 the pan supported the cheesecloth tent which was used for the 

 caging. The lower end of the tent was closed by tying it with a 

 string around the perimeter of the pan. A piece of soil containing 

 moss, grass, and humus from a swamp was cut to the shape of the 

 pan and placed within it, the grass and other plants extending 

 into the tent above. Water nearly to fill the pan was added, and 

 maintained at this level. 

 Straws and pieces of sheet 

 cork were placed around 

 the edge of the island and 

 slightly above the water. 



FEEDING CONE. 



Since Tabanus phae- 

 nops and T. punctifer are 

 very reluctant to bite any 

 host in captivity, it was 

 necessary to capture some 

 individuals which had 

 been well fed in nature, 

 in order to secure oviposi- 

 tions. This was accom- 

 plished by the aid of a 

 wire cone of ordinary 

 house screen 3 inches in 

 diameter and 8 inches 

 long (fig. 8). 



The point of the cone 

 was cut off so as to allow 

 an opening of about three- 

 fourths of an inch. A 

 gentle horse led into the 

 field was good bait. After 

 the fly had pierced the 

 skin of the host and had begun feeding it was not easily disturbed. 

 The large opening of the cone was then placed over it and so held. 

 When the fly withdrew, which it usually did not do until it had be- 

 come filled with blood, it was by careful manipulation made a 

 captive. Through the small end of the cone it was transferred to a 

 vial, carried to the laboratory, and released in the small oviposition 

 cage previously described. 



Rubber boots, hip length, were very essential. The extra-length 

 boots, aside from their use in deep water, protected the knees when 

 kneeling in swampy places in search of eggs and larvae. 



SPECIES INVOLVED. 



The species of greatest economic importance in Antelope Valley 

 are Tabanus punctifer (PL I) and T . phaenops (PI. II). Other spe- 

 cies found there are T. insuetus O. S. (PI. Ill), T. intensivus Town- 

 send, T. productus Hine (PI. IV, D, E), Chrysops coloradensis Bigot 

 (PI. IV, F), C. discalis Will., O. proclivus O. S., and C, surdus O. S. 



Fig. 8. — The feeding cone, showing method of cap- 

 turing full-fed horse-flies. 



