Page 261 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

BUTTERFLY CATERPILLARS

FAMILY Nymphalidae
DISTRIBUTION North America, Europe, and Asia
HABITAT Riparian corridors, glades, groves, parks, and yards
HOST PLANTS Many, including willow (Salix spp.), poplar (Populus spp.),
birch (Betula spp.), apple (Malus spp.), and alder (Alnus spp.)
NOTE Spiny, gregarious caterpillar that is often seen on backyard willows
CONSERVATION STATUS Not evaluated, but common

ADULT WINGSPAN
3–3⅛ in (75–80 mm)
CATERPILLAR LENGTH
2–2⅛ in (50–55 mm)
NYMPHALIS ANTIOPA
MOURNING CLOAK 259

(LINNAEUS, 1758)

Female Mourning Cloak butter ies lay eggs in “collars” of 100

to 200 eggs on the branches of the host plants. The caterpillars
hatch after ve to nine days and are highly gregarious, feeding

and moving in groups throughout development. They react in
unison when disturbed, rearing their heads and waving them
about. Such synchronous head-jerking, as well as their spines
and likely emission of repellent chemicals from a ventral “neck”
gland, are their main forms of defense.

Mature caterpillars, which have bright orange-red patches,
signaling distastefulness, leave the host plant before pupating
and wander on paths or roads. Development of this species
is rapid, as the larvae pupate as little as two weeks after egg
hatch. Adults emerge after another two weeks. Populations
of Mourning Cloaks are subject to “boom and bust” cycles,
thought to be caused by disease or natural enemy pressures.
En masse, they can be destructive: a large group can denude
a small willow tree.

The Mourning Cloak caterpillar is black with
black, branched spines, and many tiny, white
spots in broken, transverse lines. The bold dorsal
patches may be orange or red. The numerous
setae are short and white, imparting a shaggy
appearance. The head is black and shiny with
Actual size
short, white hairs.