io8 OHIO BIOLOGICAL SURVEY 



EXPLANATION OF PLATE IV. 



Syrp/uis amcricanus Wied. 



Egg from the side x 17. 

 Dorsal view of egg x 1 7. 



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

 magnified. 



Adult male about 5 times natural size. 



Larva just hatched x 59; a, posterior respiratory a])pendage. 

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

 tory appendage. 



Anterior view of larva, much enlarged, showing mouth-parts, antennae 

 etc.; a, right anterior spiracle; Ij, antennae; c, upper jaw; d, lower jaw; e, 

 the three pairs of mouth-hooks. 



Dorsal view of right anterior spiracle, highly magnified. 

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

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

 Side or dorsal vie w of posterior respiratory organ x 55 ; lettering as in Fig. 49. 

 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 esopha- 

 geal framework; e, mouth-hooks of larva. 

 Hind leg of pupa showing flexure of tibiae at a. 



.All early pupal stage from the side; a, b, and c, developing legs; d, wing- 

 pad; e, mouth-parts. 



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

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

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

 the typical shape of a parasitized puparium. 

 Lateral view of head of female x 7. 



Larva of parasite, Bassiis laetatorius, mouth-parts at a, ventral view. 

 Pupa of J>. laetaforius, ventral view. 

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



