Northern oaks are fed upon by a group of leafrollers, tiers, and shredders. Examining the caterpillars of the different species in the field with the intent of identifying them accurately can be difficult. The leafroller may be found on the same tree with the oak leaftier. Adult moths of the oak leafroller are active in July. Females lay rounded eggs in an oval mass near the crotches of twigs, covering them with scales from her abdomen. Eggs are the overwintering life stage, hatching close to when red oak buds break. Caterpillars have 5 larval instars. Young caterpillars feed by webbing together newly emerging leaves, using the leaves for protection. The upper leaf surfaces of leaves within the web are skeletonized as the young caterpillars feed. As caterpillars grow in size, they web and roll new leaves together and feed on the leaf tissue between veins. Foliage becomes shredded. Larvae are gregarious at this stage and often found within the same cluster of webbed together leaves. As larvae grow in size, their habits become solitary and they roll single leaves or lobes of leaves longitudinally or horizontally. Caterpillar activity may be completed for the season by the end of June. Pupation occurs in rolled, still green leaves in host plant crowns or attached to the trunk or vegetation below infested host plants. One generation occurs per year.
The foliage of oaks can become tattered by this insect, with only major leaf veins left intact. The oak leafroller is capable of defoliating the host tree. Historically, large outbreaks of this native insect have occurred, with caterpillars being distributed by the wind. However, luckily, this native insect has natural enemies that typically keep its population below damaging levels.
Look for webbed together clusters of leaves as oak foliage is opening in the spring.
Practices to maintain host tree vigor can help the plants to withstand the occasional outbreak of this native insect. Practices to reduce additional biotic or abiotic stressors may be helpful, such as adequate watering during periods of drought.
Trichogrammatomyia species wasps are parasitoids of oak leafroller eggs. Important pupal parasitoids include Itoplectis conquisitor (Ichneumonidae) and Phaeogenes gilvilabris (Ichneumonidae).
Acephate (NL)
Azadirachtin (NL)
Bacillus thuringiensis subsp. kurstaki (NL)
Bifenthrin (NL)
Carbaryl (L)
Clothianidin (NL)
Deltamethrin (L)
Fenpropathrin (NL)
Flonicamid+cyclaniliprole (N)
Gamma-cyhalothrin (L)
Horticultural oil (eggs) (L)
Lambda-cyhalothrin (L)
Neem oil (NL)
Permethrin (L)
Pyrethrin+sulfur (NL)
Spinosad (NL)
Active ingredients that may be applied systemically include: acephate (injection), azadirachtin (injection, soil drench), clothianidin (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.