Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 384

1040

Trichiocampus viminalis (Fallén) ( 1040-1042 )
syn. T. luteicornis (Stephens)
Poplar sawfly
An often common pest of poplar ( Populus ); sometimes
also attacking willow ( Salix ). Present throughout the
whole of Europe; also occurs in North America.

DESCRIPTION
Adult: 7-9 mm long; body mainly yellow, with the
head and dorsal part of thorax black; antennae relatively
long, black above and yellowish below; wings
subhyaline, the fore wings each with a brown
pterostigma. Larva: up to 20 mm long; head black and
shiny; body varying from glassy-green to greenish
yellow or orange, each side bearing a row of prominent
black patches; body also somewhat flattened and hairy,
the hairs arising from pale verrucae.

1040 Poplar sawfly ( Trichiocampus viminalis ).

1041

LIFE HISTORY
Adults occur from May to August, eggs being deposited
in rows within the stalks of poplar leaves. After egg
hatch, the oviposition sites appear as characteristic
depressions running along the length of the leaf stalks,
and these often betray the presence nearby of young
larvae. The larvae occur in groups, sheltering beneath
the leaves during the daytime; they also typically feed
whilst lying alongside one another. The larvae continue
to feed in groups until the final stages of their
development. Individuals then wander over the trunks
of host trees in search of suitable pupation sites. They
eventually spin double-walled cocoons in bark crevices
or amongst debris on the ground. Adults emerge shortly
afterwards. Larvae occur throughout the summer and
early autumn, there being two or more generations
annually.

1041 Larva of poplar sawfly ( Trichiocampus viminalis ).

1042

DAMAGE
Very young larvae browse on the lower epidermis, the
upper side of the leaf turning brown; older individuals
bite through the entire leaf, and sometimes cause
significant defoliation.

1042 Young larvae of poplar sawfly ( Trichiocampus viminalis ).