[113] 



COLLECTING AND PRESERVING INSECTS RILEY. 



habits. The most couvenient dimensions I find to be 12 inches square 

 and 18 inches high : the cap and the door fit closely by means of rabbets, 

 and the former has a depth of about 4 inches to admit of the largest 

 cocoon being spun in it without touching the box on which it rests. 

 The zinc pan might be made 6 or 8 inches deep, and the lower half 

 filled with sand, so as to keep the whole moist for a greater length of 

 time." 



The sand or earth in the zinc pan at the bottom of the breeding cage 

 should be kept constantly moistened, and in the case of hibernating 

 pupse the constant adding of water to the top of the earth or sand 

 causes it to become very hard and compact. To overcome this objec- 

 tion it was suggested in the Entomologists' Monthly Magazine for 

 June, 1876, page 17, that the base should be made with an inner per- 

 forated side, the water to be applied between it and the outer side, and 

 I have for some years employed a similar double-sided base, which 

 answers the purpose admirably (See Figure 124.). It is substantially 

 the same as that made for the Dej)artment by Prof. J. H. Com- 

 stock in 1879. It consists of a zinc tray «, of two or three inches 

 greater diameter than the breeding cage, which surrounds the zinc pan 

 proper containing the earth, and 

 the tube d for the reception of 

 the food-x)lant. The lower por- 

 tion of the inner pan h is of per- 

 forated zinc. Zinc supports, c c, 

 are constructed about halfway 

 between the bottom and the toi\} 

 of this pan, on which the breed- 

 ing cage rests. In moistening 

 the earth in the cage, water is 

 X)oured into the tray, which en- 

 ters the soil slowly, through 

 the perforations in the zinc pan. 

 I have found this modification 

 of very decided advantage and 

 use it altogether in the work of 

 the Division, and heartily rec- 

 ommend it. 



The base of the "\dvarium or 

 breeding cage should never be 

 made of tin, but alwaj^s of zinc. 

 If made of tin, it will soon rust 

 out. Galvanized iron may be 

 used in place of the zinc, and will doubtless prove equally satisfac- 

 tory. 



2564 8 



Fig. 123.— Insect breeding-cage or vivarium. 



