EXPLANATION OF FIGURE 32. 



Syrphus americanus Wied. 



41 Egg from the side x 17. 



42 Dorsal view of egg x 17. 



43 A small part of the surface of egg-shell showing sculpturing, highly 

 magnified. 



44 Adult male about 5 times natural size. 



45 Larva just hatched x 59; a, posterior respiratory appendage. 



46 Full-grown larva x 7 ; a, antennae; b, anterior spiracle; c, posterior 

 respiratory appendage. 



4/ Anterior view of larva, much enlarged, showing mouth-parts, anten- 

 nae, etc.; a, right anterior spiracle; b, antenna; c, upper jaw; d, lower 

 jaw; e, the three pairs of mouth-hooks. 



48 Dorsal view of right anterior spiracle, highly magnified. 



49 End or posterior view of posterior respiratory organ x 55 ; a, dorsal 

 spiracular spine; b, one of the three pairs of slit-like spiracles. 



50 Side or dorsal view of posterior respiratory organ x 55 ; lettering 

 as in Fig. 49. 



5/ Appearance of a part of the puparium externally in the region of 

 the mouth-parts much enlarged; a, right anterior spiracle with short 

 piece of trachea attached; b, lower jaw of larva; c, -upper jaw of 

 larva ; d, chitinous esophageal framework ; e, mouth-hooks of larva. 



52 Hind leg of pupa showing flexure of tibiae at a. 



5J" An early pupal stage from the side ; a, b, and c, developing legs ; d, 

 wing-pad ; e, mouth-parts. 



54 A much later pupal stage, ventral view ; a, the delicate investing 

 membrane. 



35 Dorsal view of puparium x 5 ; a, posterior respiratory organ. 



56 Outline of puparium from the side. The dotted outline is given to 

 show the typical shape of a parasitized puparium. 



57 Lateral view of head of female x 7. 



5# Larva of parasite, Bassus lactatorius ; mouth-parts at a, ventral view. 

 59 Pupa of B. lactatorius, ventral view. 



Figs. 53, 54, 58, and 59 each about 5 times natural size. 



