Head: Face yellow; brown spot below antenna, and two spots above antenna. On female, the two brown spots may form an inverted V-shape. Eyes without hair.
Antenna: Black; last joint rounded at tip, base sometimes reddish. Long bristle (arista) reddish.
Thorax: Shiny. Segment 1 (scutum) greenish-black; each side and along neck (pronotum) covered with thick yellow pile. Segment 2 (scutellum) light yellow, translucent; corners may be darker with some black hairs.
Wings: Wings clear to grayish tint. Base of wings brownish. Stigma brown.
Legs: Legs brown mixed with yellow.
Abdomen: Black with yellow (to translucent with slight green tint) stripes that do not reach to side edges of abdomen.
Segment 1 has wide yellow, slanted oval stripes starting from outer margin of base slanting in toward center, but not touching.
Segment 2 wide yellow stripe, indented at center, but never broken.
Segment 3 narrower yellow stripe, gradually narrowing to center, but never broken.
Segment 4 small spot at each side edge.
Similar Species: Didea laxa (alneti) usually has stripes all interrupted at center and touching side edges.
Size: 11 mm.
Larva: 12 to 15 mm.
Habitat: Forests and forest edges, meadows.
Food: Larva often found in colonies of Giant Bark Aphids, like Longistigma caryae, usually in Sycamore and Basswood, but also feeds on several other varieties of aphids.
Flight Time: May to September
Life Cycle: Larva are grubs, without feet or eyes. Brown with 12 bristles across first 2 segments and 12 on last segment; small spines on rest of body. Feed only on juices of mostly Giant Bark Aphids. Frass is dark purple, and helps the larva adhere to bark. Two generations. Second generation of larva only found in September to October. Pupate in mid to late October inside the last instar skin; usually attached to underside of a twig. Overwinters as a pupa.
Comments: Essex County – Lake Erie Islands.
Synonyms: Loew 1863
Didea fasciata of American authors (not Macquart 1834).
Didea pacifica also listed as synonym – doubtful, scutellum described as black.
Buffalo Society of Natural Sciences, 1875-77, Vol. 3: A List N. A. Syrphidae by Osten Sacken, pg. 63.
United States National Museum Bulletin, 1886, #31: Synopsis of N. A. Syrphidae by Williston, pp. 89 to 90.
Ohio Naturalist, 1911, Vol. 11 #7: Preliminary Report on the Life Histories of Two Species of Syrphidae by Metcalf, pp. 337 to 341.
California Academy of Sciences, 1919: 4th Series, Vol. 9 by Lovett, pg. 246.
Note: Doubtful this is a synonym of D. fuscipes due to black scutellum. On D. fuscipes the scutellum is yellow.