REPORT OF THE STATE EXTOMOLOGIST 1901 719 



It will be seen from the above table that last May was very 

 wet, rain falling 18 and 19 days respectively in the two locali- 

 ties. It is no wonder that the spring generation of the fly com- 

 pleted its transformations and that the adults were ready to 

 oviposit and infest the late sown barley. 



Signs of infestation. The first indication of attack is found 

 in the darker color of the leaves and a tendency among the 

 young plants to stool freely. The broader lower leaves and 

 the absence of a central shoot, it having been killed, are also 

 noticeable in infested fields. As the attack advances the 

 infested plants turn yellow or brown and die and the maggots 

 may be found at the base of the leaves near the ground. The 

 spring brood attacks tillers or laterals which were unharmed 

 in the autumn, dwarfing and weakening the stems so that the 

 grain usually lodges before ripening and can not be harvested 

 well. 



Rule for determining time for sowing winter wheat. This has 

 been the subject of considerable study by Prof. Webster of Ohio 

 and Dr Hopkins of West Virginia. The latter, in Bulletin 67 of 

 the West Virginia agricultural experiment station, has given in 

 considerable detail much data bearing on this subject and in 

 that bulletin he elaborates a very interesting rule for determin- 

 ing this date in various sections of the country. His results are 

 not only based on considerable scientific research, but they have 

 been confirmed by practical experience. Dr Hopkins finds: 

 1) That under similar conditions of land surface, other than 

 altitude, there is a normal rate of difference of time in the peri- 

 odical phenomena of plants and animals for all differences in 

 latitude and altitude. 2) That under normal conditions the 

 rate of average variation for the beginning or ending of any 

 phenomenon is not far from one day for every fourth of a degree 

 of latitude, or for every 100 ft of elevation. Using this rule and 

 taking as a base the time, September 25, determined by Prof. 

 Webster through observation as the date when the Hessian fly 

 normally disappears from fields about Columbus O. in latitude 

 40° and with an altitude of SOO ft, it will be found that in Gene- 

 see count}', latitude 43°, the normal period when wheat can be 

 •sown without injury by the Hessian fly is September 21. This 

 calculation is for sea. level and the date may be pushed forward 



