8 



DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



It is quite noticeable that larvae in exposed places or in poorly con- 

 structed cocoons are more frequently killed by cold than are those 

 well protected. 



As generally recommended under the control of the codling moth, 

 it will be well worth while in orchards to eliminate the favorable hiding 

 places of the larvae, particularly the wintering brood. Such places 

 are old stumps, decaying trunks, and branches of ill-kept trees, where 

 cold weather little affects the larva? or where their enemies can not 

 readily reach them. 



SPRING BROOD OF PUPvE. 



Methods of recording pupation. — On account of the fact that pupa- 

 tion takes place within the cocoon it is often difficult to record this 

 transformation without disturbing the insect by exposing the cocoon. 



Fig. 4. — Device used in obtaining pupal records of the codling moth. (Original.) 



Different workers have often used small glass vials, within which 

 the larvae have been compelled to make their cocoons and transform. 

 This method is veiy unsatisfactory when we consider the habit of the 

 larvae under normal conditions. The larva, in the construction of 

 the cocoon, either in cracks of wood or under the bark of trees, gnaws 

 off a certain quantity of particles of wood or bark and from these the 

 cocoon is largely made. Furthermore, under normal protection the 

 larva suffers less from outside fluctuating temperatures than might 

 be expected in a tube of glass. 



Formerly the writer used soft strips of wood with narrow inter- 

 spaces of one-eighth of an inch which the larvae could enter and there 

 spin their cocoons. To observe the larvae and pupae within it was 

 necessary to pull the strips apart, thus exposing the cocoon. Later 

 it was found that when a thin film of transparent celluloid was placed 

 in the interspace so as to cover the wood on one side the larvae pro- 

 duced their cocoons in a normal manner and at the same time left the 



