Species Pristiphora erichsonii - Larch Sawfly

Pristiphora erichsonii (Hartig)

native to the Palaearctic, adventive and widespread in NA (transcontinental in the north, south to NC in the east)

Eggs laid in incisions on twigs in late May-Jun(1)

Larvae feed on Larch (Larix)

Larvae overwinter in cocoons on ground(1)

Eggs are laid in rows under the bark of current terminal, lateral twigs. Hatching occurs in about 8 days and the larvae move to the foliage of older twigs where they feed in groups. Feeding is complete in 20 days and the mature larvae drop to the ground, enter the duff, and spin tough, papery brown cocoons.(2)

One generation per year with an occasional 2nd generation.(2)

A small number of larvae enter diapause and require 2 years to complete one generation.(2)

Earliest record in our area: 1880[cite:]

Repeated defoliations make trees susceptible to deadly attacks by Dendroctonus simplex(3)

Overwintering coccoons are destroyed by small mammals, especially shrews and voles.(2)

Two parasites have been imported: an ichenumon, Mesoleius tenthredinis and a tachinid Bessa harveyi.(2)

Mesoleius tenthredinis was originally effected but then the sawfly developed an immunity to it in Canada, MN, and WI.

Bessa harveyi