Phytomyza sp. 2

(Fig. 218)

Material examined. IOWA: Winneshiek Co., Cresco, Cold Water Creek Rd., 43°25'55.97"N, 92° 0'34.78"W, 16.vii.2015, em . 27.vii.2015, C.S. Eiseman, ex Symphyotrichum lateriflorum, #CSE1862, CNC564636 (1♀).

Host. Asteraceae: Symphyotrichum lateriflorum (L.) Á. Löve & D. Löve.

Leaf mine. (Fig. 218) Long, entirely linear, pale greenish; frass in long, black strips along the sides.

Puparium. Black; formed outside the mine.

Comments. We have found similar mines on Symphyotrichum lateriflorum in Ohio, but only parasitoids emerged from the puparia. Frost (1924) reported rearing “ Phytomyza albiceps Meigen ” from S. lanceolatum (Willd.) G.L. Nesom, S. novae-angliae (L.) G.L. Nesom, and S. undulatum (L.) G.L. Nesom in New York, and noted that the mines on these hosts have “a prominent central black frass line, strongly resembling the mines of the Nepticulidae ” ( Lepidoptera). The true P. albiceps is exclusively European, and Frost’s flies evidently represent one or more other species of the P. albiceps group, but Griffiths (1976) was unable to locate Frost’s or any other specimens of the P. albiceps group reared from asters in eastern North America. The mines we have observed, and those described by Frost, are suggestive of Phytomyza ciliolati Spencer (known only from Alberta), which Griffiths (1976) reared from several Symphyotrichum spp.