By Linda Williams, forest health specialist, Woodruff. Linda.Williams@wisconsin.gov; 920-360-0665

This jack pine is leaning due to damage at its base from pine root collar weevil. Photo: Linda Williams

Damage from pine root collar weevils was recently reported in Lincoln, Marinette, and Vilas counties on jack pine trees. Pine root collar weevils are known to attack and kill all types of pines, although scotch, red, and jack pine are the most common hosts in Wisconsin. The insects attack pine trees of varying sizes – from large saplings to those of small pole size. Adult weevils deposit eggs at the tree’s base; larvae then bore under bark and feed in the root collar area, effectively girdling the tree. Soil and bark near the root collar becomes blackened and soaked with pitch. Feeding larvae are visible in tunnels under the bark. Continue reading “Pine root collar weevil” →

By Linda Williams, forest health specialist, Woodruff. Linda.Williams@wisconsin.gov; 920-360-0665

After brushing away sawdust, exit/entrance holes, as tiny as the beetles themselves, become visible. A beetle is inside, peeking out. The marks at the bottom of the photo depict millimeters.

Jack pine tip beetle (Conopthorus banksianae) is a tiny bark beetle that bores into the twig tips of pines. Damage from jack pine tip beetle was observed this summer on jack pine trees in Marinette, Vilas, and Lincoln counties and on white pine in Waupaca County. These beetles attack and kill the outer 4-6 inches of twigs, leaving hollow piths. The piths can be diagnostic in determining whether an insect or disease killed the branch tip. The damage, which may appear significant since the dead needles remain on the branch tip and there can be many dead branch tips on a single tree, is rarely severe enough to be detrimental to the tree; no control is recommended.

Jack pine tip beetles kill the outer few inches of twigs. The two yellow circles show where sawdust was pushed out of the twig by adult beetles. Photos: Linda Williams

By Linda Williams, forest health specialist, Woodruff. Linda.Williams@wisconsin.gov; 920-360-0665

The tops of aspen leaves will appear off-colored when aspen blotch miner caterpillars feed within. Photo: Linda Williams

If you’ve noticed aspen trees seem a little pale lately, you are probably seeing damage from aspen blotch miner caterpillars. Typically, these leaf-mining insects only affect young aspen trees, but this year I’ve found uniform damage on bigger trees with large crowns. Symptoms include thinned crowns, off-color leaves with blisters on their undersides, and, later in the summer, curling and browning leaves. Tiny caterpillars spend their entire lives feeding within the leaf; they then pupate into the tunneled-out areas. Moths emerge in August and spend the winter in protected places.

I have reported this insect each year since 2012 in northeastern Wisconsin. This year, there were aspen leaf blotch miners in Marinette, Florence, Forest, Oneida, and Vilas counties, which is similar to where they were found last year. Although defoliation can be severe, aspen trees usually tolerate the situation well. Many affected aspen trees will send out new leaves after feeding by caterpillars ends. Although damage may appear severe, the effects on the trees’ overall health seems negligible.