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Shelterbelt Centre Pest Leaflets
Yellow-Headed Spruce Sawfly
Hosts: Colorado and white spruce
Appearance and Life History:
Adult yellow-headed spruce
sawflies emerge in the spring
just as the buds on spruce trees
are beginning to swell. Females
deposit eggs singly into the
base of new needles. Larvae
emerge within two weeks and
begin feeding on the succulent
needles. By early to mid-July
the larvae are full grown and
are about 20 mm in length. Full
grown larvae have
brownish-orange heads and
green bodies marked with six
greyish-green stripes. Fully
developed larvae drop to the
ground and overwinter in
cocoons in the soil. The sawfly
completes one generation per
year.
Damage: Larvae of the
yellow-headed spruce sawfly
initially feed on the new
needles, leaving only short
brown stubs. Once the new
growth is devoured, the larvae
move back on the branch and
feed on the older needles. By
July,
infested trees appear ragged and
yellowish-brown especially
near the tops. Heavily-infested
trees may be completely
stripped of foliage. Three to
four consecutive years of
moderate to heavy attacks can
kill the tree. The yellow-headed
spruce sawfly prefers young,
open grown trees, resulting in
extensive damage to spruce
used in plantations and
shelterbelts on the Prairies.
![yellow-headed spruce sawfly](/web/20061210134711im_/http://agr.gc.ca/pfra/shelterbelt/pest/85-2009.jpg)
Control: Infestations on a few
small trees can be controlled by
picking off and destroying the
larvae when they are first
noticed. For shelterbelts or
large trees, chemical control
can be achieved with one of the
following insecticides:
acephate, carbaryl, diazinon,
dimethoate, malathion or
permethrin. Insecticide application
should be made when damage is
first noted.
For more information contact:
PFRA Shelterbelt Centre
Indian Head, Sask. S0G 2K0
Phone: (306) 695-2284 or Fax: (306) 695-2568
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