Cerodontha (Butomomyza) sp. 1

(Fig. 23)

Material examined. MASSACHUSETTS: Franklin Co., Northfield, 276 Old Wendell Rd., 10.viii.2016, em. 22.viii.2016, C.S. Eiseman, ex Scirpus cyperinus, #CSE2931, CNC659963 (1♀) .

Host. Cyperaceae: Scirpus cyperinus (L.) Kunth.

Leaf mine. A yellowish, elongate blotch, typically occupying the space from the leaf margin to the midrib; frass in a few large, black lumps.

Puparium. (Fig. 23) Whitish to yellowish, broader in the anterior half and tending to taper posteriorly; strongly segmented; most segments with a black, elliptical patch on the ventral surface, these patches usually uniting to form a continuous ventral band with lobed margins. The puparium is firmly glued within the mine, usually roughly perpendicular to the leaf venation; typically two or more puparia lie side by side.

Distribution. MA; we have also collected leaf mines in VT.

Comments. The host, mines, and puparia all seem to match Cerodontha scirpivora Spencer, described from Ontario (Spencer 1969), but our single female keys to C. angulata . That species, however, forms a narrower, whitish mine, and its puparium is quite different, being compact and smooth (not deeply segmented), typically reddish-brown or darker, without black ventral markings, and either formed externally or loose within the mine, rather than firmly glued in place. Cerodontha (Butomomyza) sp. 1 is heavily parasitized in our experience; our three collections thus far have yielded 22 wasps ( Braconidae and Eulophidae) and a single fly.