What is an effective method for obliterating white pine weevils?
March 1, 2016 6:45 PM   Subscribe

I planted a number of native (to Michigan) white pine trees only to see them bedeviled by evil weevils. Specifically, the cause of the damage is white pine weevils and 100% of my trees were affected. Two part question: first, what are tried and true "natural" methods for controlling this pest, and second, what are its most effective pesticides, placing a high importance on minimizing collateral damage to people, flora, and fauna?

More details: I have a row of about fifteen white pine trees that are now five or six years old (planted at 1-year-old). They were growing well until last year, when the tops of all the trees showed signs of damage and I discovered weevil adults and larvae in the leaders. I trimmed and burned the trimmings immediately, but I have no idea what I missed and want to leave nothing to chance this year. I've read that Spring is the time to act.

I've put a lot of effort into planting and maintaining these beautiful trees and would very much like them to survive. (I'm somewhat emotionally attached to them.) I know I'll have my work cut out for me to coax them into growing semi-straight and developing new leaders. I'm optimistic, though, as they are still young (tallest are/were about 2m tall), but realistically I may need to cut some of them down eventually.

My preference would be not to use pesticide, but I am willing if I won't destroy the planet by doing so. Much of my property is wet during spring months with lots of frogs, and these trees, while about 200m away, are on a flat area at higher elevation. Any run-off would likely drain into the wet area with the froggies, turtles, water fowl, etc.

I would love to hear from anyone who has successfully defeated this pest, or from botanists, entomologists, toxicologists, or similar fields of study who can give pros/cons of specific treatments.
posted by tempestuoso to Science & Nature (3 answers total)
The MSU extension is really active and informed. They and their master gardeners would be a great resource for the various options to get rid of your pests.
posted by cecic at 8:12 PM on March 1, 2016 [1 favorite]

This MSU Extension article provides one pesticide recommendation (cyfluthrin) along with some treatment tips that should help to minimize environmental impacts (how to apply at the optimal time in spring, where and how much to apply for white pine weevil specifically). The free Ask an Expert service might be able to weigh in further on your concern for your aquatic friends if you don't get any advice for the first part of your question here.
posted by zizania at 9:00 PM on March 1, 2016

Definitely not an expert, but I would add to the mix of ideas: attracting birds to the area. This article claims that nuthatches, downy woodpeckers, chickadees, grosbeaks and warblers may feed on the weevil larvae. Hang out a few bird feeders and get a good bird population coming in to supplement your other efforts.
posted by hannahelastic at 9:47 PM on March 1, 2016 [2 favorites]

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