The Currant Fruit Fly. 213 



through either the tarsus or tibia with a sharp spear-pointed 

 needle. After part of the leg was severed, many flies continued 

 to feed and showed no external indication of pain ; others, how- 

 ever, flew to the windows, apparently from the shock effect of 

 the operation. Every specimen was then captured in a phial and 

 examined under a binocular microscope to determine whether 

 the same leg was cut in each lot of trypetids. 



Another method of marking currant fruit flies was with the 

 use of different colored waterproof inks. A droplet of ink was 

 applied with a small camel's hair brush to the thorax between 

 the wings, while the adults were at rest on a mosquito screen 

 wire enclosing an open window, where the ink dried quickly. 

 Each specimen received at least three coats of ink. Higgin's 

 scarlet, yellow and indigo blue waterproof inks formed an even 

 coating, and gave better results than black or india ink. The 

 difference in color between scarlet and yellow, indigo blue and 

 black could not be distinguished with certainty after marking 

 the flies. In some experiments the insect were doubly marked; 

 first by amputating part of a leg, and second with the use of a 

 waterproof ink. 



The adults were handled before and after marking in a 

 manner so that they were not injured. The flies were captured 

 by holding a wide-mouthed phial over each trypetid and then 

 the bottle was corked. After each specimen was marked, it was 

 again captured in a phial and transferred through a hole in 

 cheese cloth covering the top of a jar. The hole was plugged 

 with cotton. The bottom of the container was covered with 

 about an inch of moist sterilized sand. 



Flight of Marked Flies. 



Marked flies were set free in the field in order to determine 

 how far they might travel, and also what effect winds may have 

 on the flight. In releasing the specimens, the jar was placed on 

 the ground, the cotton plug was removed and the hole was 

 enlarged with a pair of scissors until the mouth of the container 

 YV'dS free from the cheese cloth. The orientation of marked 

 trypetids with reference to winds was carefully noted with the 

 liberaljon of each lot of insects. When a heavy wind was blow- 

 ing, the marked diptera flew and were carried by ihe wind with 



