270 REPORT OF OFFICE OF EXPERIMENT STATIONS. 



sidorod iinprju'ticahh', and late sowing of wheat is recoiniuendod, com- 

 bined with burning the stubble or plowing the field after harvesting, 

 so as to burv the insects. Ihe time for late sowing, so as to avoid 

 injury from the Hessian fly, has been studied at various stations. In 

 New York " it has been found that wheat sown after September 20 or 

 25 is usually less infested with Hessian fly than that which is sown 

 earlier. It was also possible to gain some advantage from sowing 

 narrow strips of decoy wheat about September 1. This may be 

 r.llowed to stand not more than four weeks, and as soon as thoroughly 

 infested may be destroyed. In Ohio ^ it appears that the two factors 

 which are most important in determining serious outbreaks of Hes- 

 sian fly are scarcity of parasites and warm weather in October. It 

 was found that from an entomological standpoint injury from the 

 fly may be largely prevented by late seeding. In average years, how- 

 ever, the risk of winter injury to wheat sown late enough to avoid the 

 fly appears to be fully as great as the risk from the Hessian fly. It 

 is recommended that small areas of wheat be sown from September 5 

 to September 18, according to the latitude, and that these plats be 

 watched closely for the presence of the Hessian fly. If the fly is not 

 observed by the time the plants are ten to twelve days old, the main 

 crop may be sown, otherwise it is desirable to wait a week or so longer. 

 In West Virginia " the farmers have suffered great loss from Hessian 

 fly. It is recommended that the late date for safe sowing of wheat be 

 determined by actual observations during a series of years. After 

 this has been done, it should be remembered that the dates for plant- 

 ing will vary according to the latitude. Dates based on latitude, how- 

 ever, are not available unless account be taken of altitude. According 

 to observations made in West Virginia, a difference of 200 feet in alti- 

 tude is about equal to 1° of latitude. The higher the altitude and the 

 farther north the locality, the earlier the planting. 



THE CHINCH BUG. 



t 



Chinch bugs are also one of the best known enemies of w^heat, corn, 

 and various forage plants. In Maine ^ it Avas found that complete 

 submersion in water even for a considerable period is not necessarily 

 fatal to chinch bugs. Freezing, however, while they are submerged in 

 water is almost certain to destroy them. The effect of freezing in 

 dry and moist atmospheres was compared and the chinch bugs were 

 most seriously affected Ijy freezing temperatures in a dry atmosphere. 

 In Minnesota <^ it is recommended that in the control of chinch bugs 

 all rubbish be cleared up in the fall in order to do away with places 



New York Cornell Sta. Bui. 194. ^ Maine Sta. Bui. 91. 



& Ohio Sta. Bui. 136. e >Ijnoesota Sta. Bui. S4, 



West Virginia Sta. Bui. 67, 



