THE CANADIAN ENTOMOLOGIST. 185 



THE PUPAL INSTAR OF THE FRUIT-TREE LEAF- 

 ROLLER (ARCH [PS ARGYROSPILA'). 



BY (ILENN VV. HERRICK AND R. \V. LiaBY, ITHACA, N. Y. 



For the past three years the fruit-tree leaf-roller has been 

 exceedingly abundant in New York State and has caused serious 

 losses to fruit growers. The senior author has given all the time 

 that could be spared from his llniversity duties to the fight against 

 this pest, and during the spring of 1914 it was determined to 

 prosecute the fight on a wider scale, according to plans that natur- 

 ally grew out of the knowledge that had been gained in past seasons. 

 Accordingly the junior author was established in a field laboratory 

 in Western New York among orchards seriously infested. As a 

 part of the work, it was determined to study certain phases of the 

 life history of the leaf-roller that had not been satisfactorily cleared 

 up before, and one of these points was that of the length of the 

 pupal period. This had become especially desirable in view of the 

 interesting data secured by Davidson in California.- In Bulletin 

 311 of the Cornell Station, written by the senior author, it was 

 stated that the pupal instar under insectary conditions varied from 

 nine to twelve days. This statement was based on a relatively small 

 number of pupae, whose actual instarswere determined. It seemed 

 desirable to observe a much larger number of the pup^e under as natu- 

 ral conditions as possible in order to obtain a more general average. 



Large numbers of the larvcC, nearly full-grown, were placed in 

 jars with an abundance of fresh food. These jars were in an 

 open-air insectary and under normal conditions of temperature. 

 Ever\' morning about the same hour the jars were carefully ex- 

 amined and each newly-transformed larva removed. During the 

 first part of the work each pupa was placed in a separate v\a\, wi'th 

 muslin over the top, and its record of transformation to the moth 

 kept separate. Later, all of the pupae gathered on any one morning 

 were placed in a lantern globe, together with some leaves, and 

 muslin was then tied over both ends of the globe. This arrange- 

 ment gave a clear circulation of air and maintained probably nearly 

 normal conditions of temperature and air drainage. As the moths 

 emerged, each one was rem:ived and the date recorded. The 

 following table shows graphicallv the results of the studv: 



1. ("ontrib ition from the Dep.irtmeiU of Entomology at Cornell Uiiiver.sitv. 



2. Jr Ee. Ent . Vol. fi. p. :5;)li. 



June. 191. ■) 



