Wednesday, May 14, 2014

Juniper budworm & Spider mites

I've had a few people contact me late last week about their juniper trees (sometimes called cedar trees) turning brown and needles dropping off.  I was able to get a sample sent in from the Liberty Hill area and found webbing along with spider mites.  About 10 minutes after looking at the sample, I got an email from Pat Porter about another problem case with junipers in Central Texas, but this time the culprit was the juniper budworm and was in the Bee Caves area.

Juniper budworm. Photo by Steve Darnell.
You can find more information on spider mites here.

As for the juniper budworm, the caterpillar is the damaging stage.  It is small to medium in size (depending on the instar) and green with a brown head capsule.  The caterpillars, or larvae, feed on juniper foliage and construct silken tubes where they are protected.  The tube is also where the insect pupates.  Adults are small brown moths in the family Tortricidae (also known as leafrollers).

Branch with juniper budworm. Photo by Steve Darnell.
If trees are prized landscape trees that provide screening or shade, then control may be warranted.  For management without chemicals, try handpicking the infested branch tips.  You can place them in a bucket of soapy water or double bag them and throw them in the garbage.

There are natural controls by beneficials (birds, wasps, flies, etc.) that help to mange these insects, so if you choose a chemical control method, choose wisely.  You can target caterpillars only by using Bacillus thuringiensis var. kurstaki.  Other less-toxic active ingredients include spinosad or azadirachtin.  Other possible active ingredients include things such as lambda-cyhalothrin, imidacloprid, carbaryl or acephate.

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