Pyralidae 



353 



corrugations, which open to the sides, where they remain to pupate. 

 Not more than 200 larvae should be put in each cage. Before being 

 placed in the incubator the globes and their contents are immersed in 

 water for from five to ten seconds. All excess water is drained off 

 and the water absorbed by the cardboard supplies sufficient moisture for 

 pupation. 



During the time of incubation it is necessary to look the material 

 over two or three times a week and remove the dead larvae which would 



LI- 



B 



D 



Fig. 67. — Oviposition cage for Pyrausta nubilalis. A, end view: b, frame; c. wood 

 disc closing end of cage. B, front view with lower roller removed: d, upper roller; 

 e, second roller; f, cylinder forming the cage; g, wire rods (4); w, wire screening; i, 

 wire screening cylinder for feeding cotton. C, inside end view of cage. D, lower 

 roller (hinged): r, wire rod. 



otherwise contaminate the healthy ones. The mortality among larvae 

 varies between 5% and 10%. When overwintered larvae are used the 

 moths begin to emerge in three weeks' time, but if using fresh larvae 

 collected during the late summer and fall a much longer period of in- 

 cubation is required. Emergence extends over a period of about 2 weeks. 

 A cage for oviposition (Fig. 67) consists of a cylinder 12 inches long* 

 and 5 inches in diameter suspended in a small frame (A, b) in a hori- 

 zontal position by means of a central axle on which it revolves. The 

 frame also supports a series of three rollers which hold the waxed paper 

 in place. The cage is so constructed that its sides, which represent the 

 greatest surface, are of waxed paper. The ends of the cage (A, c) are 



♦This dimension must correspond to the length of the roll of waxed paper used: not 

 all rolls are 12 inches long. 



