cut from an 80-mesh brass screen wire which was in- 

 serted with hand pressure into a groove on the inside of 

 the tubing. The groove was cut on a lathe; it was 0.8 

 mm. wide, two-thirds of the tubing thickness in depth, 

 one-eighth inch above the bottom edge of the cylinder 

 in order to provide an air space beneath the screen. 

 The screen was sealed into the groove by glacial acetic 

 acid or other suitable solvent. The top of a standard 

 petri dish 60 mm. in diameter provided the removable 

 top for the cage. 



The No. 2 cage, fig. 2E, was similar to the No. 1 

 cage, except that it was fashioned from Lucite tubing 

 3-1/4 inches in diameter (one-eighth inch wall thick- 

 ness), and had a bottom of 50-mesh brass screen wire 

 and a top that was either the top or the bottom of a 

 standard petri dish 95 mm. in diameter. This cage, like 

 the No. 1 cage, was 1-1/2 inches tall. 



The cylindrical wall of the No. 3 cage, fig. IC 

 was made from a pint-sized ice cream carton of heavy 

 waxed paper or cardboard. The bottom and the top of 

 the carton were removed, and the paper ring of the top 

 was used to retain the screen bottom, which was 30- 

 mesh brass screen wire. The top was either the top or 

 bottom of a standard petri dish 95 mm. in diameter. 



TECHNIQUE FOR CONTINUOUS MASS REARING 



Rearing of the corn borer larvae was begun in No. 

 1 cages. The food for each No. 1 cage, two pieces of 

 green string bean pods, each cut to a length of about 

 1-1/4 inches, was placed on an aluminum dish 32 mm. in 

 diameter, fig. 2C. (This dish, also called a planchet, 

 is the type used for radioactive assays.) A spacer, a 1 

 mm. diameter enameled copper wire in the form of a 

 rough M or 11', fig. 2D, was used between the pan and 

 the screen bottom in order to facilitate the circulation 

 of air and to prevent larvae from being crushed under 

 the dish when the cage was moved. Two or three com 

 borer egg masses of normal size were placed on the 

 beans in each cage, and the cage was covered with a 

 petri dish top. If the top was slightly off center, freshly 

 hatched borers wandering around in search of food were 

 able to escape over the upper rim of the cage unless a 

 filter paper disc of 55 mm. diameter was used as a liner 

 inside the top. This liner, which insured a seal around 

 the upper rim of the cage, was removed after the young 

 borers had begun to feed. 



The newly hatched larvae accepted the fresh green 

 beans without hesitation and did not wander around for 



Fig. 3. — No. 1 cages. They contain com borer larvae of first and second instars. Underneath each cage is a humidifier. 



