THE SYRPHIDAE OF OHIO 61 



A few eggs were found on the under surface of the affected leaves. 

 From such a position the larvae could easily crawl into the galls while 

 still of small size as when just hatched. 



The full-grown larvae in confinement show a negative photo-tropi.sm. 



Enclo.sed closeh' in the gall they enjoy excellent protection and have 

 for the most part an abundance of food at hand. I discovered no enemies. 



Seemingly they are paying the usual penalty for sedentary life They 

 are very sluggish. After seeking some dark protected place in the jar 

 which confined them they .scarcely move unless disturbed. These partic- 

 ular larvae were removed from the locality where similar food was not 

 available; and, although offered numerous other kinds of aphids, they re- 

 fused to eat and all died before pupating. The result of their habit of life 

 seems, therefore, to be a close restriction to one .species of prey; and proba- 

 bly they are confined ordinarily to the aphids of a single gall. Their .slug- 

 gishness would also suggest a possible further degeneration. (See pp. 39, 40. ) 



Eristalis aeneus (Fabricius) 

 (Plate VII, Figs. 131-141.) 



See the Ohio iVafura//s/, Vol. XIII, No. 5, pp. 84-89, March, 1913 



Larv.'^ — Similarto, but smaller that the well-known, "rat-tailed" \a.r\-a. oi E.h'tiax 

 13 to 15 mm. long, 3 to 4 mm. broad, 2 to 3 mm. high. Posterior respiratory appendage 

 varying from 0.5 to 0.25 mm. in diameter, extensile, 3-segmented, its length seldom 

 less than 5 mm., frequently 15 to 30 mm., occasionally as much as 100 mm. or about 4 

 inches. Ornamented at the tip with four pairs of delicate, feather-like appendages, 

 presumably homologous with the inter-spiracular ornaments of aphidophagous species. 

 Color dirty, grayish-brown. Integument translucent, flexible, bearing integumeiital 

 vestiture and double segmental hairs. There are seven pairs of pro-legs. 



Collected in the very putrid water}' material of the evaporating vats 

 at the Columbus Sewage- Disposal Plant in September, undoubtedly feed- 

 ing on the decaying, .sewage particles. 



Tuparium — Length 8 to 10 mm., height 3 to 4.5 mm., width 3.5 to 4.5 mm. vSluipe 

 that of the larva, considerably shortened, and somewhat inflated dorsally. Pupal 

 respiratory cornua located a short distance posterior to anterior respiratory cornua of 

 the larva, on dorsal side of the body; about 2 mm. in length, 0.25 mm. in diameter. 

 These cornua are provided on their distal three- fourths with several hundred short 

 rounded tubercles each ornamented on the tip with 8 or 9 radial elevations. Intern- 

 all v the cornua lead by tracheae to the prolhoracic segment of the developing nymph- 

 Larval respiratory cornua rigid at a length of 0.75 mm. 



Pupae were found attached to an iron railing surmounting the walls 

 of the .sewage vats in mid-September, emerging as adults 10 days later. 



Adult— Length 8 to 10.5 mm. Wholly dark, metallic-green shining. Kyes 

 covered with sniall, round spots. Thorax of fcnuale with grayish wliite stripes. 



