THE CIGAK CASE-BEAKEB. 39 



SEASONAL HISTORY. 



In the early spring, as the buds begin to open, the minute larvae 

 free their cases (fig. 9, d) from the branches where they have over- 

 wintered, and begin to move about in search of food. Many of them 

 reach the buds before these are opened, and eat into the soft inner 

 tissues. By the time the leaves have begun to expand practically all 

 of them have left their hibernating places and are actively feeding 

 upon the delicate leaves. 



With the growth of the larvae an addition is built to the case in the 

 form of a tube. This extends from the anterior opening on the lower 

 side of the case, and consists of fragments of leaves and silk. (See 

 fig. 9, c.) 



Fletcher observed that occasionally a larva, on reviving in the 

 spring, would leave its old case and make a new one, but as a rule the 

 old case is detached from its winter resting place and is used for some 

 time before a new one is made. 



Toward the middle of May the larva makes a case of an entirely 

 different appearance. After having undermined a sufficiently large 

 area on the leaf, the larva abandons the old case, which usually re- 

 mains attached to the leaf (PI. II, fig. 3) and from the upper and 

 lower skins of the leaf cuts out the future case. At first this is of an 

 elongated, somewhat flattened shape, but as it becomes lined inside 

 with silk it assumes a more cylindrical or cigar-shaped form. On 

 close observation it will be found that one side of the case is of a 

 hairy or woolly structure, while the opposite side is smooth. This is 

 readily explained by the fact that the case is made from the upper 

 and lower epidermis of the leaf, the lower surface being hairy and 

 the upper practically smooth. In this case the larva will continue 

 feeding for about one month. During that period it grows rapidly 

 and consumes a relatively large amount of food. The injury caused 

 at this time, though very extensive, is perhaps not more serious than 

 in the early spring, when the opening buds are mutilated or killed 

 by young larvae. 



For some unknown reason it sometimes happens that a larva with 

 a cigar-shaped case will abandon it and make a new one which is 

 apparently similar in all respects to the one previously used. The 

 writer has also observed larvae transforming in the spring cases. 

 This is probably owing to a lack of food, since these specimens, as a 

 rule, seldom attained their full size. About the middle of June the 

 larvae cease feeding and migrate from the leaves to the branches. 

 The anterior end of the case is firmly fastened to the branch by means 

 of silk, and a mass of silk is placed in the same end for the attach- 

 ment of the cremaster of the future pupa. The larva turns around 

 within the case before transforming, so that the head of the pupa is 

 30490°— Bull. 80—12 4 



