Aspen Blotch Leafminer (Tentiform leafminer)
Hosts
Aspen, poplar, and cottonwood trees.
Damage and Symptoms
The caterpillar feeding and mining cause white blotches on the underside of the leaves. Heavy outbreaks can cause reduced tree growth and branch dieback.
Life Cycle
Adult moths emerge from overwintering sites and feed on nectar. Females mate and deposit several eggs on newly emerging leaves. The larvae develop and feed within the leaf, causing blotchy looking tissue. They pupate, and the adults emerge in late summer as leaves are starting to senescence.
Management
The leafminers attack stressed trees. Normally, no treatment is necessary, and the pests are controlled by natural enemies later in the summer. Keep trees well cared for with frequent watering. If practical, pick off and dispose of the mined leaves. If chemical controls are necessary, systemic insecticides (active ingredients such as imidacloprid or dinotefuran) can be used, but have been known to be only moderately effective. The best time to spray a systemic insecticide is in the spring after bud break to allow for sufficient uptake of the chemical.
Further Information
To learn more about the topics discussed on this page, contact the Schutter Diagnostic Lab. If you suspect an infestation on your property, contact your local extension agent, the Schutter Diagnostic Lab at Montana State University, or the Montana Department of Agriculture.
This insect fact sheet is also available as a printable PDF (116KB).
Disclaimer: These recommendations are provided only as a guide. It is always the pesticide applicator’s responsibility, by law, to read and follow all current label directions for the specific pesticide being used. The authors and Montana State University assume no liability resulting from the use of these recommendations. The Montana State University Extension Service is an ADA/EO/AA/Veteran’s Preference Employer and Provider of Educational Outreach.