264 



Ajjple and Pear SncJcei' 



formed by the invagination of some of the posterior segments of the 

 abdomen. They consist of the following parts : 



(1) Supra-anal segment. 



(2) Infra-anal segment. 



(3) Chitin rod on each side, ending distally in a pointed structure. 



(4) Muscles attached to these chitinous rods. 



Fig. 21. The Eggs on Twigs. 



(iv) Oviposition. The points of the chitinous rods, between the 

 vagina opening, are concealed by the supra- and infra-anal segments. 

 When the muscles, which are attached to the proximal ends, contract, 

 the chitinous rods are pushed forward and the points project further 

 than the anal segments which are applied to the surface of the twig. 

 The egg, which is pushed forward by the circular muscles of the vagina, 



