Birch Leafminer

Characteristics

Around mid-June, adult female birch leafminer beetles will lay eggs inside newly developing leaves. Once the eggs hatch, young larvae feed for approximately two weeks in between the upper and lower layers of the leaf.

Within a couple weeks, the mature larvae will turn into adults. Birch leafminer are active between May and mid-September and can produce multiple generations in a year.

The larvae are flat with a yellowish-green and cylindrical shaped body. An adult birch leafminer is a black insect that looks similar to a wasp but is the size of a housefly.

Signs & Symptoms

Damage appears in spring to late summer as small brown or reddish-brown irregular shaped patches on the upper side of a leaf. Leafminer damage often causes the leaf’s edge to curl. Severe damage will make foliage appear brown. While this insect may cause aesthetic damage they usually do not kill their host tree. Sometimes repeated attacks may weaken a tree and make it more likely to be attacked by other insects.

Treatment & Recommendations

Treatment for birch leafminer is included in in our Plant Health Care programs. It is important to keep your birch trees healthy with regular fertilizer applications. Trees with high vigor from adequate nutrients are less likely to be a target for birch leafminer. Severe infestations may require additional treatment.

For more information on birch leafminer, talk with one of our qualified arborists.