56 OHIO BIOLOGICAI, SURVEY 



lighter in color requiring considerable magnificalion to make them visible. The seg- 

 mental bristles are short, somewhat dusky but not prominent, about equal in size. 



A comparison of the characteristics of the posterior brealhing appendages in the 

 two kinds of larvae failed to reveal anything notably different. Perhaps the principal 

 disagreement between the larvae, besides the discrepancy in size, is in color. 



While the larvae from cabbage, Phrao^iiiites etc. were all pale brown marked 

 with white and black, these may be described as follows: a third of the width on each 

 side the larva is colored a beautiful deep green. In the middle of each segment from 

 6 to lo is a branched clump of thread-like, fatty material, colored a delicate pink, 

 in front of which may be a whitish transverse bar. Between these pinkish masses 

 stretch, on the median line, the six pulsating divisions of the dorsal blood vessel, black 

 in color. These are limited laterally by broad longitudinal stripes of light brown or 

 salmon-colored visceral matter, more or less interrupted by lateral pockets from the 

 blood vessel, which are, however, not as conspicuous as those in the previous species. 

 Three grown and two younger larvae were taken near Lakeville, 

 Ohio, in Wayne County, June i6 and 17, and placed in confinemenc. 

 They were abundant at Castalia, Ohio, June 29; and were also taken at 

 vSandvisky, Ohio, a little later, and at Columbus. They were feeding 

 among Aphis r/n/n'c/s on curled dock {Ruviex crispus) and on burdock 

 {Ardiii))! )ui)iiis)\ on the former host-plant curled about the flower spike, 

 on the latter chiefly on the under side of the broad outer leaves. In the 

 case of Rumcx crispus the colors of the flower spike were remarkably 

 well mimicked by those of the larva. (See Part I, pp. 27, 28.; 



Pupa— Dimensions, average of 6: Length 6.3 mm , width 3.1 mm., height 2.93 mm 

 A comparatively short puparium, broad and high; the posterior elevation strong, 

 not quite equal to the anterior. 



If the shape of the puparium has an}' specific significance (and .so far 

 as I have observed it has been fairly constant within specific limits,) it 

 wotild seem that this form ought to be separated from S. aDicricaiius. 

 The pupa is much broader and higher. In S. aiiiericaiius for the 

 puparia measured, the ratio of length to height is 2.6 : i; of length to 

 width 2.5 : i; while in the present form it was as low as 2.15: i for 

 length to height; and 2.03 : i for width to height. 



Three pupae formed from the specimens above, June 21, the adults 

 emerging July i. Another pupated June 25, and the adult emerged July 

 4. Other larvae taken from Burdock, {^Arctium tni)ius) August 10, 

 pupated the following day and the adults emerged August 17. The 

 duration in the pupal stage was thus found to vary from 6 to 10 days in 

 captivity. 



Adult — The few variations from the more typical Syrphus a)jurica)ius 

 do not seem to be of specific value. The following might be noted : I^arger 

 specimens, length about 10 mm. Front of female with an inverted 

 V-shaped black stripe, its sides longer, parallel above; the cheeks grayish. 



