Species Acronicta betulae - Birch Dagger Moth - Hodges#9208

9208

BETULAE: refers to the birch genus Betula, the larval hostplant

wingspan 35-40 mm (1)

larva length to 35 mm

Adult: our only dagger moth with a pale tan forewing and a sharp right angle in lower part of postmedian line; much of forewing tinged with gray; hindwing tan (1)

Larva: Last instar smoky green-brown to rusty brown with long whitish hairs about sides of body. A1 and A8 but slightly enlarged. Dorsal setae from small blackened spots with 2-3 short, white setae and one, long, black seta issuing from each. Head mottled with orange to reddish patch over each lobe and abundant black "snowflaking" below red patch, mostly lighter brown and unmarked below. Integument with abundant black spinules (visible only with lens). Penultimate instar pale to bluegreen with slightly humped A1 and reddish middorsal stripe

[description by David Wagner et al - see Internet References below]

New Hampshire to Florida, west to Texas, north to Wisconsin (1)

has not been recorded in Canada, according to this list based on CBIF data

wetlands and edges of water courses containing foodplant (River Birch)

adults fly March-May and August-September (two broods)

mature larvae from May onward

larvae feed on leaves of birch, particularly - and perhaps exclusively - River Birch (Betula nigra); see remarks in PDF doc by David Wagner et al

two generations per year

Larva; larva; larva head; pre-pupal larva; adult

A detailed distribution map of River Birch (Betula nigra) in this PDF doc shows that it does not reach Canada; if River Birch is the only foodplant of Acronicta betulae, it would explain the absence of this species in Canada.

Unmarked Dagger (Acronicta innotata) forewing lacks sharp right-angle in lower part of PM line, and the species is not found south of North Carolina

Covell, p. 82, plate 17 #7 (1)

live adult images - Moth Photographers Group

live adult images mislabeled Acronicta innotata as of December 2006 (Larry Line, Maryland)

pinned adult image by John Glaser, plus seasonality and foodplant (Larry Line, Maryland)