University of Maryland Extension

Borers - Trees

clearwing borer gummosis on cherry
Gummosis from peach tree borer infestation

Many different borers attack shade trees. They may be beetles or caterpillars. Beetle borers include bark beetles, long horned beetles (locust borer) or round headed borers (red headed ash borer larva) and metallic wood borers (bronze birch borer or flatheaded appletree borer) or flatheaded borers. Beetle borers usually only attack stressed trees. Symptoms include branch dieback and exit holes. Healthy trees are usually not attacked. The best control for beetle borers is to keep trees healthy and well watered. No sprays are effective for control.

Emerald ash borer

Clearwing borers

They are the larvae or caterpillars of clearwing moths. The moths resemble wasps in appearance. Common examples are peach tree, lesser peach tree, dogwood, lilac, and ash tree borer. Larvae of these borers are creamy colored with brown heads. Signs of damage include holes in the bark, reddish frass in bark crevices or around the bottom of the tree and branch dieback. In the case of peach tree and lesser peach tree borer in flowering cherries, gummosis may be present. 


To help prevent borers, especially in Prunus, keep mulch away from the base of the tree. Keep trees well watered during dry periods. Avoid wounding the trees, especially with lawn mowers and string trimmers. Beneficial nematodes may be used to control these caterpillar borers as long as there is no gummosis. Follow package directions and spray in the evening.

peach tree borer damage
Signs of damage from clearwing borers
(peach tree borer) include holes in the
bark, reddish frass in bark crevices or 
around the bottom of the tree and branch dieback

peach tree borer adult
Adult peach tree borer



peach tree borer larva
Peach tree borer larva..all clearwing borer
larvae look very similar
ash borer adult
Ash tree borer

bronze birch borer with exit hole
Bronze birch borer and "D" shaped exit hole
bronze birch borer
Bronze birch borer larvae with frass



bronze birch borer hole
D- shaped exit hole made by bronze
birch borer
Carpenter worm larva and damage.
Carpenterworm caterpillar and damage

dogwood borer adult
Dogwood borer and pupal case
flathead apple borer
Flatheaded appletree borer



locust borer
Locust borer


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