NO. 8 ANATOMICAL LIFE OF THE MOSQUITO SNODGRASS 



35 



formed shows that it became a pupa while still within the larval cuticle. 

 It will therefore be of interest to follow the transformation processes 

 that convert the larva into a pupa. 



THE PUPAL DEVELOPMENT 



As before noted, the primary buds of the pupal wings, legs, and 

 respiratory trumpets are formed at an early larval period in pockets 

 of the epidermis beneath the cuticle, as are also those of the antennae 

 and the labium, and rudiments of the compound eyes are present in 

 the first instar. 



Fie. 13. — Pupae in natural floating position against the surface of the water. 

 A, Aedes atropalpus. B, Anopheles punctipennis. 



The development of the compound eyes of the mosquito has been 

 described by Zavfel (1907), by Constantineanu (1930), and by Sato 

 (1951a, 1953a, 1953b). The eye rudiments are first evident in the 

 first larval instar as thickenings of the epidermis just in front of the 

 larval eyes. With development of the eye pigment, the compound eyes 

 become visible externally in the second instar or the early part of the 

 third instar. From then on they increase in size as the ommatidia are 

 slowly differentiated in the epidermis. During the larval stage the 

 ommatidia are covered by the unmodified cuticle, but in the pupa the 

 cuticle over each ommatidium becomes convex and the corneal facets 

 are thus defined. After emergence of the adult the lenses become bi- 

 convex, and the ommatidia are completed in from 3 to 12 hours, but 

 the lenses may continue to thicken during the first 24 hours of adult 

 life. 



The early development of the wings and legs in the mosquito larva 

 is nothing unusual. The leg buds are always formed in the embryo, 

 and all immature insects have legs, whether external or internal. Like- 



