720 NEW YORK STATE MUSEUM 



approximately one day for each 100 feet of elevation. The 

 method of reaching this conclusion is as follows: the 3° differ- 

 ence in latitude between the two places gives an allowance of 12 

 days, that is four for each degree of latitude, and as Genesee 

 county is farther north, the 12 days may be subtracted from the 

 date given for Columbus, but before subtracting this,, the date 

 for Columbus must be brought down to a sea level calculation, 

 and as that date is September 25 at 800 feet above sea level, the 

 safe date must be eight da3^s later, or approximately one day 

 later for each 100 feet less in elevation. This brings the safe 

 date at Columbus O., were it at sea level, at October 3, and 

 bringing this date forward 12 days, the allowance made for the 

 3° difference in latitude, we have the normal date for Genesee 

 county in localities at sea level. This date, September 21, may 

 then be advanced one day for each 100 ft elevation above sea 

 level. 



At first sight this rule may appear a little cumbersome, but it 

 is really a very simple one and it certainly deserves a trial by 

 everj^ farmer troubled with the Hessian fly. If it accomplishes 

 nothing more, it gives a basis on which to begin experiments,^ 

 and we are therefore able to approximately figure the safe date 

 for any locality and then this should be checked up by past expe- 

 riences or put to the test of future use. The farther north the 

 location and the higher the elevation, the earlier may the wheat 

 be sown with safet3^ 



Parasites. The parasites of the Hessian fly are very important, 

 since were it not for them it is extremely probable that it would 

 be much more destructive than it is. The easiest way to deter- 

 mine the proportionate number of parasites in any one field is 

 to take infested stalks and breed the adult insects from them. 

 A net-covered jelly tumbler or fruit jar, taking care to avoid 

 close covers and resulting molds, will answer very well as a 

 breeding cage. Later in the season, after the parasites have 

 emerged under natural conditions, an examination of ''flaxseeds'" 

 in the field will give some idea of the relative number which have 

 been killed by these tiny friends of man, since each having a cir- 



