The larvae of a few species of moths in the genus Cameraria are common leaf mining insect pests of oak. C. hamadryadella is referred to as the solitary oak leafminer because a single larva maintains each single mine. C. cincinnatiella on the other hand is a gregarious species, so as many as 12 larvae may be found in a single leaf mine. Depending upon the species of leafminer, different species of oak may be impacted. (Details are included in the Host Plant section.) The exact life cycle details of each species will differ. Some generalizations can be made, however if in a given season a particular species is problematic, details about the timing of the life cycle will need to be understood prior to attempting to manage the insect. In general, Cameraria species may have 2-5 generations per year depending upon geographic location and climate. Both of the aforementioned species overwinter as pupae in dried, fallen leaves. Adult moths emerge in the spring and lay eggs on newly opened host plant leaves. By the end of the summer, feeding damage by these insects may be very apparent.
The feeding damage created by the larvae of these species is in the form of a blotch mine found on host plant leaves. Light to moderate infestations may be tolerated, but heavy populations of these insects may kill the leaves of their host plants. Some reports indicate that in particularly heavy population years, 80-100% of the foliage can be killed. However, it is more typical of these leafminers to cause little to no damage to their host plants - and chemical management options are often unnecessary.
Look for first generation leaf mines following the expansion of host plant leaves. Blotch-like mines turn brown.
Rake up and remove or destroy fallen leaves around susceptible host plants in the fall. In a landscape where oak are secluded from forested oak, this can be a very effective way of reducing the population locally. (Pupae overwinter in the fallen leaves.)
At least 14 species of parasitoid wasps are reported to reduce oak leafminer populations, and typically keep them below damaging levels naturally.
Abamectin (NL)
Acephate (NL)
Acetamiprid (L)
Azadirachtin (NL)
Bifenthrin (NL)
Carbaryl (L)
Clothianidin (NL)
Cyantraniliprole (NL)
Diflubenzuron (N)
Dinotefuran (NL)
Emamectin benzoate (L)
Fenpropathrin (NL)
Flonicamid+cyclaniliprole (N)
Gamma-cyhalothrin (adults) (L)
Horticultural oil (L)
Imidacloprid (L)
Insecticidal soap (NL)
Lambda-cyhalothrin (adults) (L)
Malathion(L)
Neem oil (NL)
Permethrin (L)
Pyrethrin+sulfur (NL)
Spinosad (NL)
Management may be most helpful prior to mines reaching 1/4 inch in diameter.
Active ingredients that may be applied systemically include: Abamectin (injection), acephate (injection), acetamiprid (injection), azadirachtin (injection, soil drench), clothianidin (soil drench), cyantraniliprole (soil drench, soil injection), diflubenzuron (soil drench), dinotefuran (soil drench), emamectin benzoate (injection), imidacloprid (soil drench), and neem oil (soil drench).
Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.
Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.