SYRPHIDAF OF MAINE. 209 



(the integumental vestiture). The colors are various but commonly 

 some shade of green, brown or pink, striped or blotched with white 

 or black. Usually the dorsal blood-vessel (heart-line) shows as an 

 interrupted black mid-dorsal line throughout most of the length. 



In the pupa stage this type has a somewhat characteristic shape, — 

 subovate, bulbous in front and tapering to the posterior respiratory 

 process (which retains its larval characteristics) behind. 



It is separated from the .other types I have examined in lacking a 

 conspicuous pair of anterior (prothoracic) stigmata developed and 

 pushed through the puparium for pupal respiration. These pupal 

 respiratory cornua appear to have been heretofore overlooked. They 

 are so minute that even when one knows they are present it is only 

 with the greatest difficulty that they can be demonstrated. In 

 Melanostoma mellinum (q. v. ), a species with unusually trans- 

 parent integument, they can be located readily because the tracheae 

 leading from them are easily visible. 



II. THE BORING TYPE OF LARVA. 



Body nearly cylindrical, less attenuated anteriorly. Posterior 

 respiratory process short, the spiracles convoluted, inconspicu- 

 ous; circular plate sunken. Inter-spiracular ornamentation of 

 short, palmately-branched, plumose hairs. Mouth-parts fitted 

 for rasping, of tzvo ventrally directed hooks uniting basally into 

 a mouth-hood. Segmental hairs single. 



This type is represented in my collection only by the larvae of Merodon 

 equestris, collected from Narcissus bulbs in British Columbia, for 

 which I am indebted to Dr. C. Gordon Hewitt, Dominion Entomologist. 

 These larvae are superficially much like the first type but the body is 

 more nearly cylindrical, less flattened ventrally, and less attenuated 

 anteriorly. Segmental hairs single, prominent. The posterior respira- 

 tory process has lost nearly all trace of its double nature and appears 

 as a truncated cone. The circular plates are deeply sunken and occupy 

 a central rather than a dorsal position. The spiracular slits are very 

 inconspicuous and are irregularly and much convoluted. The inter- 

 spiracular ornamentation consists of short, palmately-branched, plumose 

 hairs. 



The anterior three body segments are directed ventrad and termi- 

 nate in the mouth-parts. The latter entirely different from aphido- 

 phagous species, consisting of two black, heavily-chitinized, rasping, 

 recurved hooks, each with a small, inner, basal spur, fused basad to 

 form a heavy, black, ventrally-concave hood beneath which is the 

 mouth opening. 



I have not seen the pupa of this type. 



