lOG INSECTS INJURIOUS TO STAPLE CROPS. 



dtito for the ending of the fall period of active flight or 

 swarming of the fly at Colnmbus, latitude 40 degrees, was 

 September 25th, and that the corresponding date for 

 Wooster, latitude 40 degrees and 49 minutes, was Septem- 

 ber 20th, which he states agrees almost exactly with results 

 obtained in Indiana, and forms the base of conclusions, as 

 set forth in his Bulletin No. 107." Columbus is 800 and 

 Wooster 1000 feet above sea-level. By applying the above 

 rule and computing the date of Wooster from that of 

 Columbus, or vice ve^^sa, the same dates will be secured as 

 those determined by Prof. Webster. 



Of the various farm methods of control the most im- 

 portant is the late planting of winter wheat through the 

 Central States. In the latitude and altitude of northern 

 Ohio if this be done after September 12th the flies will all 

 have laid their eggs before the plants sprout. The time 

 of planting should be later the further south, but no arbi- 

 trary dates can be given for the whole country, as those 

 must be determined by altitude, latitude, and local condi- 

 tions. Thus in extreme southern Ohio October 10th is 

 stated to be a safe time, while in central Maryland, in the 

 same latitude, wheat may commence to be sown between 

 September 25th and October 5th. In northern Delaware 

 farmers prefer not to sow until October 1st. Prof. Roberts 

 states that though no definite dates can be given owing to 

 injury being most serious after abnormal weather condi- 

 tions, after which the dates would be different, yet that 

 "^ New York wheat-growers have learned that wheat sown 

 after the 20th to the 25th of September is usually much 

 less infested. In Ohio and Michigan, as elsewhere, it has 

 been found that wheat sown very early, i.e , about Sep- 

 tember 1st, and late, i.e., after October 1st, is but slightly 



