ZYGOBOTHRIA NIDICOLA, PARASITE OF BROWN-TAIL MOTH. 3 



specific data with regard to the length of life were obtained from 

 laboratory experiments in which various types of cages were used. 

 These consisted of: (1) Plain glass cylinders, measuring 50 by 200 

 mm., closed at one end; (2) ordinary shell vials, 22 by 100 mm.; and 

 (3) a wooden cage, which had been successfully used by Mr. J. J. 

 Culver in his life-history studies upon Compsilura concinnata 

 Meigen, a tachinid parasite of both the brown-tail moth and the 

 gipsy moth. 



The glass cylinders were rather satisfactory for two to five flies 

 each, when a bit of crunched crepe paper was placed inside to afford 

 the flies a good footing, but it was necessary to change the cylinders 



Fig. 1. — Adult male of Zygohothria nidicola. 



every few days because they quickly became dirty and sticky, and 

 this involved a good deal of work. This objection applied to the 

 shell vials as well, which in addition were found to be too small even 

 for individual flies. The wooden cage was by far the most satisfac- 

 tory. It measures about 12 inches square and 4 inches high, and is 

 fitted with a cloth bottom to facilitate cleaning after each experiment ; 

 the top is a piece of window glass of the proper size. One-inch 

 holes bored in the sides of the box and covered with fine wire gauze 

 insure good ventilation. Another opening of the same size is fitted 

 with a cork and is used for introducing the flies. Feeding is facili- 

 tated by the use of a larger opening, about 2 inches in diameter, which 

 can be closed with a wooden stopper. After the flies were^ placed in 

 this cage they were left entirely alone save for the feeding, which 



