FALL WEBWORMS: UNSIGHTLY, NOT DAMAGING by Larry Williams, UF/IFAS Extension Agent


Q:  I see webs at the ends of branches in some of my trees. Should I be concerned?

A.  These are fall webworms. These worms (caterpillars) enclose leaves and the ends of branches with silken webbing. They are found in this protective webbing consuming leaves. Although they can defoliate branches on which they are feeding, very little to no permanent damage is done to the tree. It is more of an aesthetic problem. What they are feeding on is a temporary part of the plant: the leaves. Each leaf is essentially an annual–emerging in spring, growing through summer and falling during autumn. They are not feeding on or damaging in any way a permanent part of the tree.

Although fall webworms are known to feed on more than 85 tree species, they more commonly are found on pecan, hickory, common persimmon, sweet gum, black walnut and bald cypress. Fall webworms feed on trees in nature, along roadsides, in wooded areas, etc. If you marked some of the infested trees and inspected them the following spring, you would find not even a hint of damage from these caterpillars.

We humans do much more damage in our efforts to control fall webworms than the worms would ever be able to do. Some people will prune out the branch or limb on which these caterpillars are feeding. In doing this, they are removing permanent parts of the tree. Left alone, these branches and limbs would still be on the tree and would eventually produce new leaves. Some people attempt to burn the webs, again possibly causing permanent damage to the limbs.

In my opinion, it is best to let these caterpillars run their course. They cause no permanent damage to your tree. If you do decide to spray, keep in mind that the webs these caterpillars form are difficult to penetrate with water or sprays. Also, be very careful when spraying overhead. Insecticides that contain acephate, bifenthrin, carbaryl, cyfluthrin, lamda-cyholothrin or permethrin can be used. Always follow label directions and precautions for the product you use.

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