72 



ILLINOIS BIOLOGICAL MONOGRAPHS 



[24Z 



EXPLANATION OF PLATE 

 Caudal Aspect of the Head 



Hypothetical head. 



Tabanus giganteus, female. 



Tabanus giganteus, male. 



Bibiocephala elegantula, male. 



Simulium venustum, female. 



Trichocera bimacula. 



Dixa clavata. 



Rhyphus punctatus. 



Sciara varians. 



Psychoda albipennis. 



Bibiocephala elegantula, female. 



Promachus vertebratus. 



Bittacomorpha clavipes. 



Rhabdophaga strobiloides. 



Mycetophila punctata. 



Chironomus ferrugineovittatus. 



Chironomus ferrugineovittatus, dorsal aspect. 



Mycetobia divergens. 



