Answer: Those webs in your pecan trees that keep getting progressively larger are made by the caterpillars of a moth that we know as the fall webworm. Fall webworms can harm trees if they devour most of the foliage. The tree must use reverse or stored food to maintain life, thus lowering the overall vigor of the trees. Trees weakened by defoliation are more susceptible to damage by diseases and other insects. Small webs can be pruned from the trees and destroyed. This method is the most obvious, but effective only if the webs are within reach. Insecticide sprays containing Carbaryl (Sevin), Malathion, or Bacillus thuringiensis are highly effective if used as directed. If you cannot reach the webs to spray, you may need to call a professional to rid your tree of the pests. There's nothing you can put around the trunk or on the ground under the tree to control the webworms or the adult moths. Best wishes with your pecan trees!
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