64 Trans. Acad, of St. Louis 



so like M. monodonta as to deceive even an experienced 

 eye. 



Spilomyia quadrifasdata Say. [C. T. Greene]. This 

 wasp-like fly was taken while at rest in the crevice of a 

 tree at Wickes, October 13, 1920. It looks so much like 

 Odynerus foraminatus that one would at once suggest 

 protective mimicry, excepting for the fact that in all 

 probability the two species do not appear at the same 

 time in the season. 



Chironomus tentans F. [J. M. Aldrich]. At twilight at 

 Creve Coeur Lake, many hundreds of these flies were 

 seen flying from the lake toward the shore. Earlier in 

 the afternoon a beetle, Cicindela repanda [H. S. Barber], 

 was found preying upon this fly. 



Chironomus sp. [C. T. Greene]. Over a little stream 

 in Tower Grove Park, three groups of these mosquito- 

 like flies were seen dancing at dusk, on March 20, 1921. 

 One swarm was near a foot-bridge, two feet above the 

 water, and the other two groups were about eight feet 

 above the ground. Each group comprised a hundred or 

 more insects. They hovered or poised in the air without 

 changing their positions, with their heads all pointing 

 southward for many minutes at a time ; then for a time 

 they would change to another form of maneuvering, danc- 

 ing in and out, up and down, facing in various directions. 

 In a short time, however, they always resumed the for- 

 mer behavior. Out of the group a mated couple would 

 occasionally dash away and escape, but darkness was 

 falling so fast that I failed to ascertain from which type 

 of dance the mating occurred. 



The gnats and midges of this family bear great gen- 

 eral resemblence to the Culicidae. Sharp says,* ''They 

 occur in enormous numbers, and frequently form dancing 

 swarms in the neighborhood of the waters they live in." 



Tahanus lineola Fabr. [F. Knab]. Found dead in the 



•lM«cto, Pt. II, p. 468. 



