The Western Sycamore borer is one of the several species of clearwing moth which attacks coast live oaks, sycamore trees, and other high-value ornamental trees in our area.
Dying limbs, rough or gnarled bark, trunk and branch swellings, sap exudation, and sawdust-like frass (excrement), are good indications that wood-boring insects have infested a tree. Sycamore moth larvae bore beneath tree bark and push frass, sometimes mixed with gummy tree exudate, from their tunnels. Small piles or a scattered dusting of frass mark the location of tunnel openings and clearwing pupal cases may be visible.
Western Sycamore borer feeding can damage the plantï¿½s food- and water-conducting tissues and cause tree bark to become gnarled or rough With some clearwing species, such as those that attack pine, sycamore, and willow, these host trees tolerate the feeding, which apparently causes no serious harm. Feeding by other species, however, can weaken or kill branches. Branches that larval tunneling has weakened may break and fall, especially during windy weather. Sometimes entire trees may die. Other types of wood-boring insects produce similar damage.
The adult moths fly during the day or at twilight, and their yellow and black coloring resemble that of paper wasps or yellowjackets. Adults display wasplike behavior by intermittently running while rapidly fluttering their wings. They differ in color depending on species and sex. They are often yellow, orange, or red on black or dark blue.
The sycamore borer is prevalent in California's sycamore trees and it also infests oak readily infests our coast live oaks.
Sycamores can tolerate extensive boring by this insect, although the cosmetic damage caused by the insect to the tree bark can be unsightly.
Utilizing the ARBORjet Tree I.V. injection system we are able to treat for this pest in whatever tree it attacks. However, there are times when the tree's bark is rendered too porous by this pest's damage when a trunk injection is impractical. When this is the case, properly timed pesticide applications to the exterior trunk can be useful in the control of this pest.
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