Ll. Lloyd 



13 



also bear spine bosses, and in one case there is an asymmetrical one 

 on the fifth segment. Where these additional ones are not developed, 

 minute hairs can be seen replacing them, evidently vestiges. 



This instar becomes quite opaque early in its development and it is 

 therefore not possible to tell by the movements of the pharyngeal pump 

 how long it continues to feed. After the eyes and other organs are well 

 developed, if it is removed from the leaf its mouth stylets wave to and 

 fro as though they were still functional. Considerable growth in depth 

 also takes place after the adult eyes are distinct. If it is removed from 



Fig. 4. Mature scale (pupa) of A. vaporariorum. ( x 130). 1. adult eye, 2. thoracic breathing 

 fold, 3. caudal breathing fold, 4. vasiforra orifice. 



the leaf shortly before emergence the mouth stylets break ofE short by 

 the case and have evidently ceased to function except as an anchor. 

 About this time a copious excretion of honey dew takes place and the 

 insect then lies tolerably free inside the old larval skin. 



The duration of the scale stage was noted on a variety of plants 

 which were examined before use to ascertain that they were free from 

 the pest. They were then heavily infested with the fly for one or two days. 

 After this the fly was cleared from them and they were enclosed in muslin 

 sleeves. The hatching of the eggs and the emergence of the adults were 



