Page 596 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

MOTH CATERPILLARS

FAMILY Noctuidae
DISTRIBUTION From Morocco and northern Spain through central and eastern
Europe (excluding the Mediterranean basin), Asia Minor, and the
Caucasus; southern Scandinavia east across Russia and southern
Siberia to China, Korea, Japan, and Russian Far East
HABITAT Damp woodlands, marshes, bogs, and other damp habitats
HOST PLANTS Alder (Alnus spp.) and birch (Betula spp.); also Rowan
(Sorbus aucuparia)
NOTE Caterpillar of damp places that has a broad, yellow stripe
CONSERVATION STATUS Not evaluated, but local in western Europe due to habitat loss
from drainage

ADULT WINGSPAN
1 ⁄ in (43 mm)
CATERPILLAR LENGTH
1 ⁄ –1⅝ in (40–42 mm)
ACRONICTA CUSPIS
LARGE DAGGER
594
(HÜBNER, [1813])

Large Dagger caterpillars hatch from eggs laid singly on the
underside of host plant leaves. The larvae feed openly on
the leaves as they develop. In their final instar, when their
distinctive yellow dorsal stripe fades to white, the caterpillars
descend to pupate in a cocoon formed within rotten wood or
under bark. There are one or two generations annually from
June to October. The daggerlike markings on the forewings of
adults give this and other Acronicta species their common name.

At early instars, the Large Dagger and the Grey Dagger
(Acronicta psi), which shares a similar geographic range, are
quite difficult to tell apart. When more mature, both have
a broad, yellow stripe along the back, but the Large Dagger is
easily distinguished by the much smaller protuberance on the
fourth segment and the distinct, long pencil of black, white-
tipped hairs extending from it. The Large Dagger is also more
restricted by food plant and habitat than related species.

Actual size The Large Dagger caterpillar is gray and
moderately hairy, with a broad, yellow dorsal
stripe that turns white before pupation. Laterally,
it has orange-red marks and blocks of irregular,
black spots. There is also a broad, white stripe
low down. On the fourth segment, a low, blackish
hump arises, with a long pencil of distinctly
black, longer, white-tipped hairs. Near the tail
end is a gray hump.