104 OHIO BIOLOGICAL vSURVEY 



EXPLANATION OF PLATE IL 



Syrphus torvKs Loew 



Adult male, natural size and enlarged. 



Larva, natural size and enlarged; a, anterior spiracle; b, posterior spiracle. 



Antero-ventral view of head and mouth-parts much enlarged; a and b, 



upper and lower jaws partially separated; c, outer pair of mouth hooks; d 



and e, two inner pairs of mouth-hooklets; f, antennae; g. anterior spiracle; 



h, sense papillae. 

 Fig. 12 Anterior spiracle of larva highly magnified. 

 Fig. 13 Posterior breathing appendages much enlarged; a, one of the six caudal 



spiracles. 

 Fig. i^ Puparium from above, natural size and enlarged; a, posterior spiracles. 

 Fig. 15 Puparium from side showing line of clea vage for escpe of adult. 

 Fig. 16 Head of female in profile. 



