Time for the sawfly watch to begin

Where have all the sawflies gone? My columbine are blooming without skeletonized leaves. My currents are coming on strong with leaves entire, and I have been watching closely. I haven’t even had calls to the Cooperative Extension Service about larch sawflies.

Well, truth be told, I may be a little early in my watch. I just checked past year’s data and this is what I found. The dates in the following chart represent the first and last reports received over the last five years on three sawfly pests here in the Valley.

The worm is actually the immature form of a sawfly, a close relative of bees and wasps, though the adults tend to look more like flies than bees. The earlier in the lifecycle the pest is found, the easier it is to control and the less damage done to the plants.

The columbine sawfly, Pristophora aquiligae, is the one to look out for if you grow columbine. They generally start on the bottom and interior leaves, and are easy to miss until the damage is readily apparent. They can be very difficult to see due to coloration and their small size early in the cycle. They may be found on the underside of the leaves or climbing up the stem from the surrounding vegetation.

The imported currant-worm, Nebatus ribesii, is a common pest of currants and gooseberries, often defoliating entire plants seemingly overnight.

The larch sawfly, Pristiphora erichsonii, was first reported in the Mat-Su in the late 1990s. It can defoliate larch or tamarack in what seems to be a relatively short time period. Larch trees do grow new foliage again in a couple of weeks.

However, in the Interior, repeated annual defoliations have resulted in top-kill and in some instances, tree death.

Cooperative Extension Service has information on the lifecycle, cultural controls and guidelines to reduce damage by these pests and others.

For more information, contact pfcompton@alaska.edu or 746-3472, or stop by the Mat-Su/Copper River Cooperative Extension Service, 809 South Chugach, Suite 2, Palmer.

Pam Compton is an integrated pest management technician for the Mat-Su/Copper River Cooperative Extension Service.