Page 145 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

BUTTERFLY CATERPILLARS

FAMILY Lycaenidae
DISTRIBUTION Canada, western United States (Washington State to California),
and northern Eurasia
HABITAT High, windswept rocky ridges and scree slopes
HOST PLANTS Saxifrage (Saxifraga spp.), primrose (Primula spp.),
and legumes (Fabaceae)
NOTE Northern hemisphere caterpillar probably vulnerable
to climate warming
CONSERVATION STATUS Not evaluated, but widespread and common

ADULT WINGSPAN
1–1⅛ in (25–28 mm)
CATERPILLAR LENGTH
⅜ in (10 mm)
AGRIADES GLANDON
ARCTIC BLUE 143

(DE PRUNNER, 1798)

The eggs of the Arctic Blue are laid singly under leaves or
on flowers; the larvae eat buds and flowers. The caterpillars
develop to the second or third instar and then overwinter.
In some areas and seasons, they may overwinter twice. Actual size
The caterpillars produce considerable frass, which may betray
their presence. They feed mainly at night and hide by day.
Predators and parasitoids appear to take a great toll on eggs
and young larvae.

Arctic Blue caterpillars are distinguished by their deep magenta-

purple coloration, which camouflages them surprisingly well
among the red stalks and stems of their saxifrage host plants.
Other lycaenid caterpillars may have reddish or purplish
instars, but few have the color intensity of Arctic Blues. The
coloration may vary on other host plants, with green larvae often
found on legume host plants. The Arctic Blue caterpillar is dark purplish red
with a contrasting white ventrolateral stripe, a
black dorsal stripe bordered white on each side,
and black, diagonal marks dorsolaterally. Its
setae are numerous, short, and dark. The head
is black but usually hidden from view when the
caterpillar is resting.