REPORT OF THE STATE ENTOMOLOGIST 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 800 ft, it will be found that in Gene- 
see county, 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 
