66 OHIO BIOLOGICAI. SURVEY 



Didea — "Larvae probably aphidophagous, as Col. Yerbury found 

 D. intermedia not uncommon on Furze ( Ulex') bushes which were infested 

 with an Aphis. The ts^pe representative of D. fasciata was bred, but I do 

 not know from what." Verrall, British Flies, p. 326. 



D. fasciata v2iX. fuscipcs is aphidophagous; see p. 58. 



Lasiophthicus — "Mr. G. C. Bignell has bred C. pyrastri from a 

 hva which he found on a Rose-bush {Rosa)\ the larva was green with a 

 purplish- white dorsal stripe, and the perfect insect emerged on June 17 

 after having been in pupa three weeks. He also bred it from Aphis bras- 

 sicae, A. pntni, and horn 2in Aphis on Knapweed {Centaiirea).'' Verrall, 

 British Flies, p. 336. See p. 40 ante. 



Syrphus — Probably all aphidophagous. See pp. 54-57. 



Riley, Rept. Dept. Agr. 1889, 351, mentions the larva preying on 

 Grain Aphis, Siphonophora avenae. 



Allograpta — A. obliqua is aphidophagous. See pp. 58, 50. 



Riley, Rept. Dept. Agr. 1889. 351, mentions the larvae feeding on 

 Siphonophora avenae. 



Xanthogramma — A', eniargniata. Williston notes a specimen in 

 Riley's collection labeled "found under bark of cotton tree, Fla., April 20, 

 '74." 



Verrall, British Flies p. 448 says "the larva has been reared from 

 heaps of turf." 



Mesogramma — In Insect I^ife. I, pp. 5-8, Fig. i, and 2., p. 115, 

 Riley and Howard report the occurrence of "The Corn-feeding Syrphus- 

 Fly, ( Mesogramma polita Say)" in New Jersey (1885) and Florida (1886}. 

 The larvae were sent in on corn with the report that they were not doing 

 evident damage. An examination of the contents of the alimentary canal 

 showed the presence of partly crushed pollen grains, and the larvae fed 

 upon the pollen grains of fresh corn "tassels" offered them. In the field 

 they clustered on the plants in the axils where the upper leaves joined the 

 stalks, the latter half of August; remaining and increasing in size for two 

 weeks after the corn was cut. Another patch blossoming early in Sep- 

 tember became infested at that time. Adult insects emerged September 

 7 to 15 from larvae taken Aug. 31 and pupating a few days later. In 

 Florida larvae were found (May and June) feeding, not on the pollen 

 grains, but on the leaves, the stalk, and soft discolored places in the stalk. 



The whole transformation from egg to fl}^ is completed in less than 

 three weeks. The egg hatches in from three to four days; the larva 

 matures in from eight to ten days and the fly appears in from eight to 

 thirteen davs. 



