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Michael Wheeler: Fall webworms on trees no true cause for concern
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It has begun. The annual appearance of webbing in trees along the roadways and woods in the county has started.

As the days get shorter and shorter, the appearance of fall webworms in trees around the county becomes more prominent.

Fall webworms are caterpillars that use their silk webbing to form protection from predators as it feeds on leaves of more than 100 different types of trees. Some of the most common trees we see them infest are black walnut, mulberry, elm, sweetgum, willow, apple, ash and oak. It is a native insect that ranges from Canada to Mexico.

The sign of fall webworms in a tree are relatively easy to spot. They will create a nest at the end of branches, and as they need more leaves, they expand the size of the nest to meet their needs.

In general, fall webworms are nothing to be too concerned about. If a tree is healthy, it will withstand an infestation. Most deciduous trees can tolerate losing most of its leaves, especially during this time of year when fall leaf drop is just around the corner.

The time to be concerned with an infestation of fall webworms is when small trees are trying to become established or when trees are sick or stressed. In general, the damage they cause in hardwoods is purely cosmetic and does not cause long-term damage to the tree.

With that in mind, chemical control is generally not required. If you need to treat an infestation, start with insecticidal soaps, horticultural oils or bacillus thuringiensis. These products will provide control of the caterpillar when it is small, but not harm other insects or predators who feed on them.

If you have large caterpillars on a tree, then consider using bifenthrin or cyfluthrin. When using any of these products, you must make contact with the worms inside the webbing. So be prepared to break into the nest to expose the mass of caterpillars inside by using a broom handle or something of that nature.

Michael Wheeler is county extension coordinator for the UGA Cooperative Extension office in Hall County. You can contact him at 770-535-8293, www.hallcounty.org/extension. His column appears weekly and on www.gainesvilletimes.com.

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