DISCUSSION OF INJURIOUS INSECTS. . 91 



Mr. Washburn said he had found that carbon bisulphid as ordi- 

 narily used will not kill the eggs of the Mediterranean flour moth. 



Referring to Mr. Conradi's paper, Mr. Webster said that a study 

 of weather conditions would often enable us to, in a measure, fore- 

 cast the abundance of insects. Thus, a cold, Avet spring was likely to 

 be followed by invasions of aphides, army worms, and cutworms. 

 He had thought that the cold weather prevented the parasites of 

 aphides from becoming abundant early in the season, but did not so 

 affect the aphides. He had found the poison-bran mixture to work 

 well in practice against invasions of cutworms. He had used it in 

 large onion fields with success. He fully agreed with Mr. Burgess 

 as to the importance of the jointworm in Ohio. From information 

 received during the past season, he was quite certain that much of the 

 damage charged up to the wheat midge had really been due to the work 

 of jointworms. In northeastern Indiana some farmers had hesitated 

 about sowing wheat last fall through fear of its ravages another year. 

 The Cryptopristus had not seemed to him to fulfill expectations in 

 holding the jointworm in check. He was rather surprised that Pro- 

 fessor Washburn should have found no Hessian flies in Minnesota. 

 One of his assistants, Mr. George I. Reeves, had been stationed in 

 North Dakota during the entire summer, and had been assigned to 

 Hessian ffy investigations. Mr. Reeves had found that there were, 

 in 1905, probably two well-defined broods of the Hessian fly, besides 

 a continual reenforcement by adults continuing to emerge from last 

 year's stubble (1904). The past might have been an unusually 

 favorable season, but another year ought to give definite results. 

 From present indications the maps showing distribution of the Hes- 

 sian fly in the United States will have to be greatly modified. As 

 yet there is no ground for believing that the pest occurs south of 

 the Arkansas River, and rarely, if at all, west of the one hundredth 

 meridian, except, of course, on the Pacific coast. 



Mr. Hinds said that in recommending fumigation of corn with 

 carbon bisulphid Mr. Conradi had said that it was not recommended 

 for corn intended for seed. Was the unusual strength recommended 

 the reason for this exception ? 



Mr. Conradi answered that in one experiment, in which soft corn 

 was subjected to the carbon bisulphid for twenty-four hours, the 

 germ seemed to be injured to a great extent. Under such conditions, 

 therefore, it would seem advisable to lessen the strength somewhat 

 in the case of corn that was to be used for seed. In the case of cow- 

 peas he had used 2 pounds to 50 bushels of grain without injury. 



Mr. Marlatt said that in the experience of the Seed Section of the 

 Bureau of Plant Industry of the Department of Agriculture fumi- 

 gation with carbon bisulphid was deemed perfectly safe and not 



