Page 493 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World

MOTH CATERPILLARS

FAMILY Geometridae
DISTRIBUTION Europe and across northern Asia to Siberia
HABITAT Woodlands, parks, and gardens
HOST PLANTS Range of deciduous trees, including birch (Betula spp.),
oak (Quercus spp.), and elm (Ulmus spp.)
NOTE Twiglike caterpillar that is found among leaves of deciduous trees
CONSERVATION STATUS Not evaluated, but scarce in parts of its range

ADULT WINGSPAN
1 ⁄ –2 in (40–50 mm)
CATERPILLAR LENGTH
2 in (50 mm)
ENNOMOS AUTUMNARIA
LARGE THORN 491

(WERNEBERG, 1859)

The female Large Thorn lays her eggs on the leaves of deciduous
trees in fall, and the eggs overwinter and hatch in spring. The
caterpillars remain in the canopy, feeding at night on the leaves
of a wide variety of deciduous trees. During the day, the
larvae stay motionless on the branches, relying on their

camou age to avoid predation. Their development to the nal

instar often takes several months. They then pupate in a cocoon
spun between leaves. The moths eclose up to six weeks later.

Like all members of the family Geometridae, the caterpillars
have a looping movement, giving them the generic name
“loopers.” In August, the caterpillar drops to the ground,
where it pupates in a cocoon in the leaf litter or under moss.
The adult emerges a few weeks later. Unusually, the moth is
a fall-flying species with the adults on the wing during
September and October. The Large Thorn is becoming scarce
in some countries, such as the United Kingdom, likely because
of urbanization.

Actual size

The Large Thorn caterpillar has a twiglike
appearance. The at, squarish head is brown or
gray brown, and the body is brown, in varying
shades that resemble tree bark. As well as a long
and slender body, there are warts along its length
to reinforce the twig camou age and a pair of
large claspers at the end of the abdomen.