PARASITISM OF BROWN-TAIL MOTH IN AMERICA. 



151 



shape) was held in position by a tack which passed through it into 

 the wooden strip. The end of this cone, passing through the bottom 

 of the cage, permitted a third glass tube (/) similar to the two above 

 mentioned, to be held in position. No further support to this tube 

 was needed than that afforded by the cone itself. 



In using this cage a mass of cocoons of the brown-tail moth was 

 placed in the tray, and the cover was put on with the several tubes 

 in position. Tachinid maggots issuing from the prepupal caterpillars, 

 or pupae contained in the cocoon mass, in attempting to seek the 

 earth would pass through the bottom of the tray and be conducted by 

 the stiff paper funnel into the lower tube, where they were quickly 

 noticed and easily re- 

 moved. All other 

 parasites, as well as 

 the brown-tail moths 

 themselves, when they 

 emerged, were at- 

 tracted by the light 

 into the two upper 

 tubes, and could be 

 similarly removed 

 with little difficulty. 

 (See PL V, fig. 1.) 



By the aid of this 

 contrivance we were 

 enabled to secure a 

 quantity of the larvae 

 of the unknown tach- 

 inid, already men- 

 tioned, within a few 

 minutes after they 

 had issued from the 

 host, and thereby de- 

 termined that the fail- 

 ure of this species to 

 pupate was in no way due to the unnatural surroundings. Some- 

 times the tubes were partly filled with damp earth, in order that 

 these larvae might immediately come in contact with it, and at other 

 times the larvae were removed as soon as they dropped and placed 

 upon earth similar to that which they would naturally have encoun- 

 tered had they issued from cocoons in the field under wholly natural 

 conditions. 



The use of these cages also saved a large amount of exceedingly 

 painful work which would otherwise have been necessary in determin- 

 ing whether or not Parexorista chelonise was present in any of the 

 field collections. 



Fig. 10. — Rearing cage for tachinid parasites of the brown-tail moth* 

 a, Paper funnel; b, cleats holding paper funnel in position; c, tray; 

 d, wooden strip on outside of cage; e, paper cone connecting paper 

 funnel a and glass tube /; h, h, paper funnels supporting glass 

 tubes g, g. (Original.) 



