Agromyza parca Spencer

Material examined. IOWA: Allamakee Co., Footbridge Farm, 22.vii.2018, em. by 14.viii.2018, J. van der Linden, ex Poaceae, # CSE4946, CNC1643675–1643677 (2♁ 1♀); NORTH CAROLINA: Durham Co., Durham, 17- Acre Wood Preserve, 8.v.2017, em. 4.v.2018, T.S. Feldman, ex Dichanthelium, # CSE4482, CNC1135677–1135678 (1♁ 1♀); Scotland Co., Laurinburg, St. Andrews University, 10.v.2017, em. 6–14.v.2018, T.S. Feldman, ex Dichanthelium, # CSE4502, CNC1144099–1144100 (1♁ 1♀); Wake Co., Morrisville, Lake Crabtree County Park, 6.vi.2018, em. 25.vi.2018, T.S. Feldman, ex Dichanthelium scoparium, # CSE4695, CNC1135686 (1♁).

Tentatively identified material. NORTH CAROLINA: Scotland Co., Laurinburg, St. Andrews University, 3.v.2017, em. 6.v.2018, T. S. Feldman, ex Dichanthelium, # CSE4503, CNC1144101–1144102 (2♀).

Hosts. Poaceae: Dichanthelium clandestinum (L.) Gould, D. * scoparium (Lam.) Gould, Glyceria canadensis (Michx.) Trin., G. striata (Lam.) Hitchc. (Eiseman & Lonsdale 2018).

Leaf mine. On Dichanthelium, eggs are inserted near the leaf margin, associated with a cluster of feeding punctures. The usually gregarious larvae initially mine along the margin toward the apex, then turn around and form a large, dirty whitish upper surface blotch with generally distributed, liquidy, greenish to brown frass. Concentric feeding lines are present in some mines. Mines on Glyceria may be on the lower leaf surface and the photographed examples do not have associated feeding punctures.

Puparium. Yellowish-brown to reddish-brown; formed outside the mine.

Phenology and voltinism. In Massachusetts, larvae feeding from late June to mid-July emerge as adults from mid-July to early August; larvae collected in mid-August yielded some adults in early September, with some females emerging the following spring (Eiseman & Lonsdale 2018). In Iowa, a larva found feeding in late July emerged as an adult about three weeks later. In North Carolina, larvae collected in early May did not emerge as adults until the following spring, whereas a larva collected in early June yielded an adult later that month.

Distribution. USA: *IA, MA, NC, TN.