THE SYRPHIDAE OF OHIO n 



Everj^one recognizes that it is always desirable and often exceedingly 

 important to be able to identify an insect in its immature stages; especial! v 

 as a larva. This phase of Entomolog\- has been too much neglected. It 

 is true that none of the immature stages presents such a variety of char- 

 acters as does the imago, and distinctive description is consequent! v much 

 more difficult. Yet I believe it will be found possible, at least among the 

 Syrphidae, to describe the larvae and pupae in such a way that they can 

 be definite!}' recognized. 



It was with two points in mind, therefore, that the life-history .studies 

 which were the basis of this paper, were carried on from 1909 to 191 1. 

 An attempt was made (i) to determine definitely what species are 

 aphidophagous in Ohio, of how much importance they are, and something 

 of their life-hi.stories and biological relations; and (2) to make possible 

 the specific identification of immature stages. Natural!}- the subject has 

 by no means been exhausted. Such results as were achieved have been 

 reported from time to time in a series of articles in T/ie Ohio Naturalist:^ 

 In these articles nine species are carefully described in their immature 

 stages; eight of them, so far as I am aware, for the first time. Brief 

 synopses of these articles together with notes on one or two other 

 species will be found on the following pages. A goodly number of Oliio 

 species witli the aphidophagous habit must still rrmain to be described. 



ACKNOWLKDGEMENTS 



I am liapp}' to acknowledge here, briefly but none the less sincerely, 

 ni}- obligations to those who helped me in various ways in this work. 

 First of all to the Professors of Entomology at the Ohio State University: 

 Professor Herbert Osborn whose inspiring encouragement has been most 

 helpful; Professor James S. Hine who has collected and studied the Syr- 

 phidae very carefully and who most generously supplied me with every- 

 thing he had in the way of specimens and literature as well as with help- 

 ful advice and criticism. The list of species in Part III is ba.sed largely 

 on specimens collected and originally identified by him and now embraced 

 in the University collection of Diptera. 



To my brother, Professor Z. P. Metcalf of We.st Raleigh, N. C, I 

 am indebted for many helpful suggestions, for certain materials for study, 

 and for a critical reading of the manuscript. Professor W. M. Wheeler of 

 Harvard University supplied me with larvae and ]iupye of the genus 



*The. {)iiio yniarnHM. Vol. XI, Nu 7, pp ;;:i7-;i41, 2pl. .M:i.v. J'.Hl. 

 Vol. XII, No. 1, pp. 397-104, !pl. Nov. 1911. 

 VoLXTI, No.5, pp. 477-JSS, Ipl. M.ir. liUJ. 

 Vol. XII, No 8, pp.r.:«-54l, )pl..liiiio, I'.iii;. 

 Vil.X'II.No. .">. p]) ,S!-0:j. yj.il.M,iiTli.l'.il:j. 



