Curcidionidae 481 



little more than 1 mm. long and of obscure coloration. Its presence is 

 indicated by feeding punctures (deep round holes) in the thalli of the 

 duck-weed and by the mines of its larvae. These mines are long and 

 very irregular tunnels through the thalli. The damage that they do to 

 the plants is often conspicuous. Adults are most easily obtained by 

 rearing them from infested thalli. 



Sphagnum is excellent material on which to place the larvae just 

 before pupation. As they become ready to pupate they leave the floating 

 plant and move about on the open water, evidently in search of a suit- 

 able place. When removed to a small handful of moist sphagnum they 

 crawl into the cup-like leaves and pupate there. 



The moss should be placed in a shallow dish and covered with a 

 tumbler. Thus as the adult forms emerge they can not escape. 



BOLL WEEVIL CULTURE* 



F. A. Fenton, Oklahoma A. and M. College 



i. Storage of material. No adequate information. Weevils are sus- 

 ceptible to temperature exposures of io° F. for short periods. Probably 

 the best storage temperature is 50 F. Only adult weevils will store 

 for any length of time. 



2. Food. Cotton fruits in following order of preference: Square, 

 bloom, young boll, medium-sized boll, mature unopened green boll. 



3. Ovi position. Immature anthers are necessary for egg develop- 

 ment, but some oviposition will occur when bolls are fed upon. 



4. Cages. Large lantern globes over pans filled with moist sand are 

 first choice; jelly tumblers second. 



5. Rearing. To keep strong stock, fresh unpicked cotton squares 

 are needed for oviposition. These must not be picked but left on the 

 plant until normal shedding time which will occur in approximately 

 6 to 7 days. Some weevils will develop in picked squares, but stock will 

 die out about F 2 generation. Optimum temperature 8o° to 84° F. 

 (variable). 



6. Adult recovery. Place shed squares in partitioned cages over 

 dampened sphagnum moss. Each compartment of cage equipped with 

 glass vial for recovery of weevils upon emergence from pupae. 



GRAIN WEEVILS 



D. L. Lindgren, University of Minnesota 



TWO species of grain weevils, Sitophilus granarius and S. oryzae, are 

 common pests of stored grain. The former, the granary weevil, is 

 more abundant in the north, and the latter, the rice weevil, in the south. 



* See U. S. D. A. Tech. Bull. 112 for further details. It is practically necessary to 

 have growing cotton. For technique see pp. 9-11, 41. 46-48. 



