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Tree Canopy Defoliators

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Defoliators (an adult or larval insect) eat or destroy the leaves or foliage off of trees and shrubs most commonly in two phases, early season (early spring to summer) and late season (later summer to fall.) In this post we'll share the difference between the two defoliators and the different treatment options. 


Early season defoliators typically cause the most damage. In the regular cycle of a tree, leaf development is fueled by carbohydrates, produced during photosynthesis. Each year these reserves or carbohydrates are replenished when new leaves emerge. When an adult or larval insect attacks the canopy of a tree, the tree then has to make a new set of leaves. Depleting the trees “reserves.” In high infestations, defoliation may cause loss of most or all of the foliage and thus stunt the growth of trees, due to the under supplied levels of carbohydrates. This type of early defoliation causes serious havoc on tree health and can lead to decline and even death. However, if early defoliation is caught soon enough a systemic (soil or root injection) treatment may be a viable option.

Late season defoliators are not as harmful to the tree as early season. However, plant healthcare treatment still needs to take place, to keep populations low. Late season defoliators slow down the natural process of a trees natural cycle, even if the felt effect on a tree is not as strong. Those that emerge in both early and late season can be a serious nuisance to any homeowner. It is best to take immediate action, upon first notice. Late fall is a good time to treat for known cases of piercing/spring sucking insects that feed directly in the phloem (soft scale, aphids whiteflies, etc), with a highly soil-bound systemic via soil injection (imidacloprid, acelepryn). These treatments remain in place for uptake and longer-lasting control next spring.

Check out the Tree Bugs page for more information on early season defoliators versus late season defoliators. 

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