Biology Reference
In-Depth Information
941
Family
CIMBICIDAE
Medium-sized to large, stout-bodied, fast-flying
sawflies, with distinctly clubbed antennae.
Cimbex femoratus
(Linnaeus) (
941-942
)
syn.
C. sylvarum
(Fabricius)
Large birch sawfly
A common but minor pest of birch (
Betula
), including,
occasionally, nursery and garden trees. Present
throughout Europe.
DESCRIPTION
Adult:
20-22 mm long: head, thorax and abdomen
black, but sometimes partly, if not entirely, reddish
brown or yellow; antennae and tarsi yellowish orange;
wings mainly clear, with brownish margins.
Larva:
up
to 50 mm long; head pale yellow, with distinct black
eyes; body green, marked with yellow and with a
distinct black, blue-centred dorsal line; body distinctly
wrinkled and covered with white verrucae; spiracles
black.
941
Female large birch sawfly (
Cimbex femoratus
).
942
LIFE HISTORY
Adults occur from May to July, eggs then being laid in
the stalks of birch leaves. The larvae feed from July to
September. When at rest, they remain curled up on the
underside of an expanded leaf and, in spite of their size,
often escape detection. Fully fed larvae pupate in large
(
c.
10
20 mm), barrel-shaped, reddish-brown cocoons
spun on the host plant. Adults emerge in the following
spring.
×
942
Larva of large birch sawfly (
Cimbex femoratus
).
DAMAGE
Larvae cause slight defoliation but damage is of little or
no significance.
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