Common Tree Pests & How To Spot Them

Sep 27th 2021

Tree pests and diseases overtake millions of urban trees each year, withering away previously dense and lush tree canopies. Particularly active in the warmest months of the year, tree pests are often thought to only target dead or weakened trees. But, Florida is home to a significant number of tree insects that can likewise wreak havoc on healthy trees. This makes identifying tree pests early on critical to ensuring the health and longevity of your trees. Here, our master arborists share information about five common tree pests and the best ways to identify them.

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Aphids are common tree insects that feed on tree sap using piercing, sucking mouthparts. These soft-bodied insects eat away at sap within tree leaves and tree stems, leaving behind honeydew, a sticky syrup-like substance. Large aphid infestations can stunt the growth of new leaves and cause leaves to curl, turn yellow, and become misshapen. These pests reproduce rapidly, forming massive colonies that can quickly overwhelm even a healthy tree. In addition to the destruction they cause to trees, aphids can also be quite challenging to identify, as adult aphids typically grow to only one-quarter of an inch in length. Moreover, aphids exist in various colors, including pink, green, gray, and black. Look out for yellowed leaves, curled, and stunted as well as leaves and stems with sap on them.

Tent Caterpillars

Tent caterpillars are common tree pests that exist in two types: western tent caterpillars and eastern tent caterpillars. Western tent caterpillars primarily attack willow, poplar, cottonwood, and fruit trees throughout the western United States. However, Florida residents should look out for eastern tent caterpillars, which mostly feed on oak, aspen, sugar maple, and other shady, hardwood trees. These tree pests usually appear in the early springtime, around the same time that trees start to bud, both in the state and throughout the eastern half of the nation. Fortunately, eastern tent caterpillars typically do not cause damage that kills trees, but they can cause some degree of twig, branch, and leaf loss. To spot an infestation, look for the presence of large, silken tents, stunted tree growth, and stripped leaves.

Gypsy Moths

One of the most notorious tree pests, gypsy moths defoliate more than a million forested acres of trees each year throughout the United States. When they infest trees, this invasive species has a ripple effect on wildlife and overall tree health. These fast-growing gypsy moth caterpillars defoliate trees by consuming their leaves. The gypsy moth may infest yards and landscapes in the warm summer months, even unexpectedly falling from tree branches. As leaves from a tree emerge in early spring, the moths deposit masses of eggs on tree bark, which hatch into destructive larvae. The moth's larvae defoliate many different hardwood trees, but they are particularly damaging to oak trees, birch trees, elm trees, and maple trees. To spot gypsy moths, look for yellow-colored, teardrop-shaped egg infestations (egg masses may contain up to 500 eggs) on tree trunks in the springtime.

Emerald Ash Borers

The emerald ash borer is an invasive tree pest that kills millions of ash trees every year. This flat-headed wood borer can be difficult to spot, as adult borers are extremely small in size. These pests have yellow-brown-colored abdomens and green, iridescent backs. Trees infested with the emerald ash borer may exhibit serpentine, an S-shaped feeding place containing significant amounts of sawdust and frass. Another telltale sign of an infestation of emerald ash borers is D-shaped holes located in tree trunks. These entry points allow emerald ash borers to invade spaces deep inside trees, destroying critical tree layers and tissue. Emerald ash borers lay their eggs outside of trees, on the tree's bark, and when hatched, their larvae have dark spines and white bodies. Inspect your ash trees for crown dieback from the top-down as well as yellowing foliage.

Scale Insects

Scale insects live in trees and feed on the inner parts of a tree's bark, causing leaf yellowing, stunted tree growth, branch dieback, and eventual tree death. These sap-sucking insects are notoriously difficult to control as they resemble small bumps on leaves, twigs, and branches and don't appear like most insects. In addition, scale insects leave behind layers of sooty mold, a primary sign of their presence. The optimal time to treat these pests is during late winter before they reemerge in the springtime. Additional telltale signs of scale insects include yellowing or browning leaves, premature leaf drops, twig and branch dieback, and slowed tree growth. Due to their easy-to-miss appearance, your best bet for ridding your trees of scale insects is with the help of an experienced arborist. Contact SkyFrog Tree Service to schedule tree care today!