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Pristiphora erichsonii (Tenthredinidae)
the larch sawfly
Adults:
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Adults are 6 to 9 mm long and are characterized by an orange band around the abdomen.
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Larvae:
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Mature larvae are about 16 mm long, have a black head and a grey green body with a whitish underside. Note that the larval "eye" is a single ocelles (c.f. stemmata of lepidopterous larvae).
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Damage:
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Eggs are deposited in pockets cut into one side of terminal shoots, causing them to curl in a characteristic fashion. Newly hatched larvae feed along the edges of needles on new shoots but soon move back to feed on the needle clusters of older twigs. Larvae tend to feed in groups, stripping a branch before moving to another. If numerous, the tree will be severely defoliated, resulting in a loss of annual wood increment.
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Principal Hosts:
Tamarack (Larix laricina), western larch (L. occidentalis) and to a lesser extent, subalpine larch (L. lyallii).
Economic Importance:
Larch sawfly is a very destructive pest in eastern North America. Repeated defoliations have caused extensive tree mortality. In British Columbia, epidemics have occurred during the 1940s, 60s and 70s, however, no tree mortality has been attributed to this insect.
References and Links:
EAG: 476-479; FC: 450; FPL 12.
See HForest and JP17.
Additional Images:
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