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.|
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.|
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.