''Pristiphora erichsonii'', the larch sawfly, is a species of
sawfly
Sawflies are the insects of the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay ...
. The adult sawfly resembles a black
wasp
A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. ...
, is about ½ inch in length with a thick waist and has brown to orangish markings on the abdomen. Larvae have black heads, gray-green bodies with white undersides, and are about 15–18 mm long when full grown. Larvae occur in groups and characteristically curl their bodies upward in a "J" shape when disturbed.
In the spring when
larch trees are leafed out and the new growth is expanding, the female sawfly can be seen depositing eggs in new shoots near the branch tips.
Damage symptoms
Egg-laying causes shoots to curl as they grow. Larvae occur in groups or clumps and are very obvious when present. Defoliation is rarely complete but trees can appear very thin crowned.
Most trees are very tolerant of defoliation and trees generally recover during the summer, however severe defoliation over several years can weaken the trees causing them to be less likely to survive a harsh winter.
Life cycle
Winter is spent in the soil as a prepupa. Adults emerge in late spring and females lay eggs in elongating shoots. Larvae feed on needles for 3–4 weeks, generally in late June and early July. However, emergence can be delayed for some individuals larva can be present throughout the summer.
Origins
The Larch Sawfly is native to Europe, however introduced into North America in the mid to late 19th century. It was first spotted in Quebec in 1882. It was then later spotted in British Columbia in the 1930s.
References
Gallery
Image:Larch sawfly 01.jpg, Larch sawfly, early instar larva
Image:Larch sawfly 02.jpg, Larch sawfly, early instar larva
Image:Larch sawfly 03.jpg, Larch sawfly, late instar larvae
Image:Larch sawfly 04.jpg, Larch sawfly larvae about to pupate
Image:Larch sawfly 05.jpg, Larch sawfly pupae
Tenthredinidae
Insects described in 1837
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