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Acleris (Croesia) semipurpurana

Oak leaftier caterpillars, frass, and damage. Photo: Natural Resources Canada.
Scientific Name: 
Acleris (Croesia) semipurpurana
Common Name: 
Oak Leaftier
Growing Degree Days (GDD's): 
7-35 GDD's (early - mid April) Base 50F, March 1st Start Date (Source: Cornell Cooperative Extension.)
Host Plant(s) Common Name (Scientific Name): 
Red oak (Quercus rubra) *Preferred host.
Scarlet oak (Quercus coccinea) *Preferred host.
Insect Description: 

The caterpillars of the oak leaftier are often associated with the oak leafroller (Archips semiferana), discussed elsewhere in this guide. Oak leaftier caterpillars are approximately 1/2 inch long at maturity, and off-white to light green in color with a light brown head and dark colored thoracic legs (brown to black). Caterpillars hatch from eggs in approximately mid-April to early May. The earliest hatched caterpillars are capable of entering the buds of their host plants even prior to their expansion. When population outbreaks occur, it is possible that all of the buds of a tree may be killed. Any leaves that survive often expand with holes created before they even opened, damage similar to other early season feeding caterpillars like winter moth (Operophtera brumata). Caterpillars of the oak leaftier create webbing and fold leaves, which provides protection for older caterpillars that eventually feed out in the open. Once mature, the caterpillars drop from their hosts to the ground on a strand of silk, where they pupate on the ground. The adult moth of the oak leaftier emerges approximately in June and July and females lay their eggs on the twigs or bark of their hosts. Moths are approximately 15 mm long and yellow with brown markings. A single generation occurs per year.

Damage to Host: 

Oak leaftier caterpillars cause damage to newly opening buds of oaks. Damage to the buds or bud death can occur. Buds that survive to expand and produce leaves may reveal leaves with many holes from early feeding. Foliage attacked by this pest can be webbed and/or folded. Damaging populations of the oak leaftier do not occur every year. However, outbreaks are possible and when they do occur, it may be in a cycle of several years. Springtime defoliation can result in worse injury to trees, as this disrupts the healthy cycle of photosynthesis and production of sugar stores for the winter.

Historically, populations of the oak leaftier were reported as heavy in 1966 in New York, New Jersey, and Connecticut. In Pennsylvania and West Virginia infestations increased in size and intensity, and the Monongahela National Forest had (at the time) 10,000 acres of oak stands suffering heavy mortality (Forest Insect Conditions in the United States, 1966, US Forest Service).


Look for damage as described above to host plant leaves in late April or early May. Canadian researchers have isolated sex pheromones that may be used with traps to monitor for the adult moths of this insect (Silk et al., 1997). 

Cultural Management: 

Adequate watering, particularly after any rare defoliation events caused by oak leaftier, may help trees recover from the stress caused by premature leaf loss. Other practices to promote tree health and vigor may also help reduce the impact of this insect on the tree.

Natural Enemies & Biological Control: 

At least one genus of tiny, parasitoid wasp in the family Eulophidae (Dimmockia spp.) is reported as a parasitoid of the oak leaftier (Kirkland, 2009). 

Chemical Management: 

Azadirachtin (NL)

Bacillus thuringiensis subsp. kurstaki (NL)

Bifenthrin (NL)

Carbaryl (L)

Chlorpyrifos (larvae) (N)

Flonicamid+cyclaniliprole (N)

Gamma-cyhalothrin (L)

Horticultural oil (eggs) (L)

Lambda-cyhalothrin (L)

Neem oil (NL)

Pyrethrin+sulfur (NL)

Pyrethrins+piperonyl butoxide (L)

Spinosad (NL)


When used in a nursery setting, chlorpyrifos is for quarantine use only.

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.

Read and follow all label instructions for safety and proper use. If this guide contradicts language on the label, follow the most up-to-date instructions on the product label. Always confirm that the site you wish to treat and the pest you wish to manage are on the label before using any pesticide. Read the full disclaimer. Active ingredients labeled "L" indicate some products containing the active ingredient are labeled for landscape uses on trees or shrubs. Active ingredients labeled "N" indicate some products containing the active ingredient are labeled for use in nurseries. Always confirm allowable uses on product labels. This active ingredient list is based on what was registered for use in Massachusetts at the time of publication. This information changes rapidly and may not be up to date. If you are viewing this information from another state, check with your local Extension Service and State Pesticide Program for local uses and regulations. Active ingredient lists were last updated: January 2024. To check current product registrations in Massachusetts, please visit: .