THE SYRPHIDAE OF OHIO 57 



The yellow abdominal bauds ma}- be a little wider, the second one with 

 angular projections in the middle, in front and behind. Hind femora in 

 the female blackish brown on the proximal half. 



Syrphus torvus Osten Sacken 

 (Plate II, Figs. 9-16.) 

 See the Ohio Naturalist, Vol. XI, No. 7, pp. 341-344, May, 191 1; also 

 N.J. Ag. Col. Ex. Sta. Bull. 72, pp. 11- 14, 1890, "Plant-lice and 

 how to Deal with Them," J. B. Smith. 



Larva— Length 10-12 nmi., width 3-4 mm. Color brown-pink, mid-dorsal blood 

 vessel rather prominent, no integumeiital vesliture except the light colored segmental 

 spines. (From the figure given by Ur. Smith (/. c.) and his description, — larva"wiih 

 a ver}- rough skin, beset with minu'.e bristly little hairs." I take it that heret'ers to a 

 geneial covering of what I have called integumental spines, and n :>t to tlie twelve 

 segmental bristles of each segment; and if so, my observations do not agree v\ith his.) 

 Spiracular slits longer and narrower than in Didea fasciata. Inter-spiracular projec- 

 tions not prominent. Lateral mouih-hooklels present. Abundant among .Ipliis 

 brassicae on cabbage in Autumn Also found preying on Lo)ioislii^ijia caiyae. 



Puparium — Length 8 to 8.25 mm., width 3.5 to 4.3 mm., height 3.75 to 4 mm. 

 Tes'.aceous — brown, smooth. 



Adult — Length 10 to [2.5 mm. Gray spot on the cheek. Eyes pubescent. First 

 abdominal band interrupted, all attaining the lateral margin. 



Syrphus xanthostomus Williston 

 (Plate \T, Figs. 81-87.) 



Seethe Ohio Naturalist Xo\. XIII, No. 5, pp. 81-83, March 1913. 



Larva — Length about 10 mm., width 3.75 to 4 mm. Fat, thick, grub-like, 

 sluggi>h larvae, strongly arched, dorsally; wrinkling prominent. Color very pale 

 pinkish-yellow, dorsal blood vessel not conspicuous. Skin bare except for the short, 

 light colored, segmental bristles. Jaws unusually short. Posterior repsiratory 

 appendage a fourth longer than broad, inter-spiracular spine short, blunt, spur-like, 

 rather prominent. Dorsal spiracular spine short, compressed, its breadth about equal 

 to diameter of approximate circular plate. 



Larvae were found full grown at Cedar Point, Jul>' 7, 191 1. They 

 were taken on poplar or American aspen (Populus tieniuloidcs Mx.) in 

 the well known galls of Pemphigus vagabundus Walsh, on which they 

 were feeding. Probabh' each larva is dependent for its food suppl>- on 

 the aphids within the single gall which it inhabits. 



Puparium — Length 7.2 mm., height 3.5 mm., width 3.8mm., exce])tionly inflated 

 dorsally, posterior inflation equal to that anteriorly. Duration in jnipal stage, seven 

 to eight days. 



Adult — Length 11 to 12 mm. Lateral margins of thorax distinctly yellowish 

 poUinose, scutellum wholly yellow. The three principal bands of the abdomen 

 broader than the black interval, attaining the lateral margins in nearly tlieir fuU 

 width. 



