Page 272 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

BUTTERFLY CATERPILLARS

FAMILY Nymphalidae
DISTRIBUTION Western North America, from Alaska to New Mexico
HABITAT Mountain areas above 3,300 ft (1,000 m) elevation, including
meadows, streams, roads, and trails
HOST PLANTS Currant (Ribes spp.) and elm (Ulnus spp.)
NOTE Caterpillar protected by spines and often by spiny host plants
CONSERVATION STATUS Not evaluated, but common

ADULT WINGSPAN
1¾–2 in (45–50 mm)
CATERPILLAR LENGTH

1⅜–1½ in (35–38 mm)
POLYGONIA GRACILIS
HOARY COMMA
270
(GROTE & ROBINSON, 1867)

Hoary Comma caterpillars hatch from eggs laid singly, or in
groups of three or four, on the underside of host plant leaves
four or five days earlier. Feeding from the leaf edges, they
create jagged holes. The caterpillars rest on stems or leaves of
the host, usually on the undersides, where they are hidden from

aerial predators. Concealment and camou age a ord the larvae

some protection, as do the spines of some of their host plants.
Chemicals emitted from a small ventral gland near the head may
also repel some attackers. Shelters are not constructed. In later
instars, caterpillars disperse, with only one or two per shrub.

The caterpillars go through ve instars, each taking about ve

days to complete, and pupation occurs on or near the host plant;
the pupal period lasts about nine days. The butter y adults are

long-lived (up to 12 months), and there is only one generation

a year. The ight period extends from mid-March to October,
and adults overwinter.

The Hoary Comma caterpillar is black anteriorly
with orange or mustard spines, and the posterior
area is black with nearly solid, white frosting
dorsally. The black sides have rusty-orange,
wavy lines resembling links in a chain. The head
is shiny black with two conical “horns.” Some Actual size
caterpillars become bright rusty orange
anteriorly prior to pupation.