Plainview, in Macoupin county, and at Princeton. A great mass 

 of detailed facts has thus been accumulated, a full presentation and 

 complete discussion of which will be given in due time in one of 

 the reports of the State Entomologist of Illinois, and probably in 

 an Experiment Station bulletin also. It is expected, however, that 

 at least another year's work of this kind will be done before a 

 final report is written up. In the meantime we printed an illus- 

 trated pamphlet defining our problem and conveying such infor- 

 mation concerning it as we could then collect, and we have now 

 prepared this preliminary paper giving the main practical results 

 of our operations of 1915 and a description of the lines of work 

 which have led to them. 



To make sure that everything may be readily understood as 

 we go, it seems worth while to recall a few elementary facts in 

 the life history and economy of the insect. (Fig. 1). The winged 

 codling-moth is properly called a mofh, belonging to the order 

 Lepidoptera and to the family of leaf-rollers. Its larva, commonly 

 known as the apple-worm, is consequently a caterpillar; and, like 

 other caterpillars, it changes when, full-grown into a dormant, mo- 

 tionless pupa, having first spun itself up in a loose cocoon. From 

 these pupae come out in course of time the winged moths, male and 

 female, which pair for the fertilization of the eggs, in the females' 

 ovaries, without which, of course, the eggs will not hatch. The 

 fiat, scale-like eggs are laid on the leaf or the surface of the apple, 

 or sometimes on the twigs, and from them the larvae are hatched 

 which presently enter the apple and begin their life of mischief. 

 When full-grown, they leave the apple and spin their cocoons in 

 some sheltered spot. The insect passes the winter in the larva or 

 apple-worm stage, changes to the pupa when the weather begins to 

 warm up in spring, and gives out, a little later, the moths of the 

 first generation, which lay the eggs for the apple-worms to fol- 

 low. (Fig. 2, 3, 4.) 



Two questions of special practical interest present themselves: 

 one, the number of generations in a year; and the other, the time 

 when the eggs of each generation hatch to give out the young 

 worms. To these we may add a third question, as to variations in 

 the number of generations and the times when the young larvae of 

 each appear in different parts of the state, and in successive years 

 of unlike weather conditions. It was the main object of our work 

 of this year to answer these questions as definitely as possible after 

 a single season's precise experiments. 



We can now say positively that there were two complete gen- 

 erations of the codling-moth in both central and southern Illinois 

 this season, and that there was a small or partial third generation 

 at Olney and farther south. We can say furthermore that the 



