44 



Nel)raska. Cockerell concludes there are three full genei-ations near 

 Me.silla Park, N. Mex. Aldrich in 1900 stated that there were three 

 generations in Idaho, and in 1903 concluded after a series of breeding- 

 experiments that there was a partial third generation at Lewiston. 

 At various times writers have m^de assertions that in the warmer 

 sections of the United States a partial fourth brood Avas produced. 



In carefully sifting all these statements the writer finds man}^ points 

 which throw dou])t upon and render them of but little value, principally 

 l)ecause definite dates and localities are not given. The date and exact 

 localities are often of as much importance to future workers, and per- 

 haps of more importance, than the observation itself. 



METHODS BY WHICH THE NUMBER OF GENERATIONS MAY BE 



DETERMINED. 



From the nature of the case the determination of the number of 

 generations of the codling moth is a most difficult problem to solve 

 accurately. The methods used must be scrutinized carefullv, and all 

 possible sources of error must be taken into consideration oi" elimi- 

 nated. The correctness of a conclusion can be assured only by exact- 

 ness in methods and b}" corroborative evidence secured by ditferent 

 methods. Observations made in orchard examinations have constituted 

 one of the methods largely followed. Although observations are of 

 great value when used in connection with other methods, they often 

 lead to erroneous conclusions when used alone, as it is possible to 

 obtain evidence of the condition of an orchard onl}- from the study of 

 a ver}" small portion of it during a very short period. Past conditions 

 are often unknown, and conclusions obtained are largely based upon pre- 

 conceived ideas. If a large number of insects can be bred throughout 

 the season, much valual)le data can be secured and the pro])lem solved 

 beyond any doubt. As yet we have no records of breeding experiments 

 carried on throughout the season with the necessar^^ accurate data. 

 The writer has attempted many times to breed the insects throughout 

 the season, but has always failed, usually on account of some unfore- 

 seen difllculty which caused the experiment to end. However, it is 

 believed that with proper care and experience this breeding can be 

 successf ulh' done. Breeding the insect and harmonizing the results of 

 the breeding by observations in the orchards has been the method 

 most used in working upon this question. By breeding the insect 

 through parts of its generations valuable data have been secured, 

 which, if pieced together and corroborated by other methods, are 

 almost as valuable as if the insect had been bred throughout the season. 

 Man}^ entomologists have neglected to increase the value of their 

 breeding experiments by keeping the insects under conditions of tem- 

 perature and moisture ditferent from those prevailing in the orchard 

 and keeping no record or a veiy fragmentar}" record of the tempera- 



