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European Pine Sawfly
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Taken from the B.Y.G.L. (Buckeye Yard and Garden Online) Newsletter
Contributing Authors: Pam Bennett, Joe Boggs, Cindy Meyer, Jim Chatfield, Erik Draper, Dave Dyke, Gary Gao, David Goerig, Tim Malinich, Becky McCann, Bridget Meiring, Amy Stone and Curtis Young |
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Joe also noted that landscapers in southern Ohio should be monitoring for overwintered European pine sawfly (Neodiprion sertifer) egg hatch. The eggs were inserted last season into individual slits (one egg per slit) cut along the edges of newly expanded pine needles by female sawflies using their saw-like ovipositors. The eggs scars are still visible, appearing as rows of yellowish-brown spots running the length of the needle. Preferred hosts include Scotch, mugo, red, jack, Table Mountain, and Swiss Mountain pines. White and Austrian pines are occasional hosts.
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The sawfly larvae are caterpillar-like in appearance, and have bulbous, shiny-black head capsules. They feed in colonies which may include 10-20 larvae. First instars are mostly grayish-green, which makes them difficult to detect among the needles. The first instar larvae are too small to consume entire needles. They feed along the edges of needles producing clusters of curled, wiry, straw-colored needles. Later instars develop faint grayish-white longitudinal stripes and they consume entire needles. Sawfly larval colonies can rapidly defoliate branches. Fortunately, there is only one generation per year in Ohio and the impact the sawfly larvae have on tree health is limited since the larvae only consume last year's needles. Unfortunately, larval feeding damage can seriously reduce the aesthetic appeal of infested trees. Tufts of newly expanded needles appearing from new growth on otherwise denuded branches produces a striking "poodle tree" effect.
Most insecticides labeled for use on pines will control this sawfly. This includes soil drench applications of imidacloprid (e.g. Merit); however, the applications must be made in the fall. As with all sawflies, the larvae will not be killed using products based on the naturally occurring bacterium Bacillus thuringiensis (Bt). An alternative approach to controlling localized populations is to simply knock the colonies onto the ground and dispatch them using the "sawfly two-step dance." Thus far, no population of the European pine sawfly in the U.S. has shown resistance to this effective and highly satisfying control method. |
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