temperature of the season has very much to do with the rate at 

 which the successive changes go on, the time when the different 

 generations make their appearance, reach their largest numbers, 

 and disappear, and the size and importance of the last or third 

 generation of the year. It is also certain that 1914 was a very 

 different year from 1915 thruout southern Illinois in respect not 

 only to temperature and other weather conditions, but also to the num- 

 bers and importance of the last generation of the codling-moth. Fin- 

 ally, we are convinced that the nice and successful timing of 

 spraying operations to the life history of the insect, such that 

 effective poisons shall be on the apples when they are most needed 

 and will be most destructive to the young apple-worms, requires 

 a careful and intelligent observation of the course of events for 

 each year, since no two years can be exactly alike, and one can 

 never tell in advance what sort of a season to expect. We believe 

 that, for the best results, an observing station with an experienced 

 man in charge, equipped with apparatus of observation and ex- 

 periment, is necessary for each of the principal fruit sections of the 

 state; but we have to propose a practical method by wmich the 

 fruit-grower can himself follow the course of events thru the 

 season in a way to serve fairly well the necessities of the case, 

 enabling him to learn for himself and for the fruit growers of his 

 region about when spraying should be done and how often re- 

 peated to protect his crop. The remainder of this paper is in- 

 tended to show how these conclusions were reached and upon what 

 evidence they rest. 



We may begin with the equipment of the Olney station and 

 the method of its use. We had there a rain-gage to give us a rec- 

 ord of the rain-fall, a self-recording thermometer which gave us, 

 on a tracing across a ruled diagram, the temperature reading for 

 every hour of every day in the season, a pair of thermometers for 

 determining the humidity of the atmosphere, a self-recording ap- 

 paratus also, for determining the atmospheric humidity continuously, 

 the record being made as a continuous line upon a ruled diagram, 

 and a peculiar and comparatively new instrument, known as an at- 

 mometer, the object of which was to show the joint effect of tem- 

 perature, moisture, and movement of the air as exhibited in the 

 rate of evaporation from a wet surface. Continuous records were 

 kept with all these kinds of instruments from the beginning to the 

 end of the season; but for reasons which we need not stop here to 

 explain, we have found the temperature record the only one of any 

 very important use in our present inquiry. Similar instruments were 

 supplied to L. M. Smith at Ozark, and to W. P. Flint for use at 

 Plainview. (Fig. 5.) 



