Page 341 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

MOTH CATERPILLARS

FAMILY Lasiocampidae
DISTRIBUTION European Alps, Scandinavia
HABITAT Upland coniferous forests and moors, and scree slopes with
low-growing shrubs
HOST PLANTS Various, including alder (Alnus spp.), birch (Betula spp.),
Vaccinium spp., and willow (Salix spp.)
NOTE Brown, hairy caterpillar of limited distribution
CONSERVATION STATUS Not evaluated

ADULT WINGSPAN
1¼–1 ⁄ in (31–43 mm)
CATERPILLAR LENGTH
¾–⅞ in (20–22 mm)
ERIOGASTER ARBUSCULAE
DWARF BIRCH SPINNER 339

FREYER, 1849

Dwarf Birch Spinner caterpillars hatch from eggs laid by the
female moth in large clusters on the host plants. The larvae
stay together, spinning a communal silken tent over the leaves
and stems of the plant during June and July. They feed in the
safety of the web, but on sunny days they can be seen basking in Actual size
the sun. After their nal molt, the caterpillars become solitary.

To pupate, they drop to the ground and spin a tough, pale
yellow cocoon that lies in the leaf litter or just beneath the soil
surface. They overwinter in their cocoons.

The adult moths eclose and are on the wing in May and June,
usually the following year with a single generation. If the
conditions are unfavorable, however, it is not unusual for
the species to overwinter for more than one year to increase its
chances of survival. While the silken webs of the caterpillars are
a relatively common sight within their range, the night- ying

moths are rarely observed.

The Dwarf Birch Spinner caterpillar is dark
brown to black in color and covered in hairs of
varying length, some white and others orange
brown. There is a dorsal row of pale yellow
spots and a lateral line of smaller, creamy spots.
The head is black and the prolegs are brown.