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Gracillaria syringella (Formerly Caloptilia syringella)

Lilac leafminer damage. Photo: Whitney Cranshaw, Colorado State University, Bugwood.
Scientific Name: 
Gracillaria syringella (Formerly Caloptilia syringella)
Common Name: 
Lilac Leafminer
Growing Degree Days (GDD's): 
246–363, 1388–1644, Base 50F, March 1st Start Date (Source: Bob Childs, UMass Extension and Cornell Cooperative Extension.)
Host Plant(s) Common Name (Scientific Name): 
Ash (Fraxinus spp.)
Deutzia (Deutzia spp.)
Euonymus (Euonymus spp.)
Japanese tree lilac (Syringa reticulata)
Lilac (Syringa spp.) *Preferred host.
Mountain ash (Sorbus spp.)
Privet (Ligustrum spp.) *Preferred host.
Insect Description: 

The lilac leafminer is a European native that is now found throughout the Northeast and parts of eastern Canada. It was first reported in the United States around 1923. Adult moths are reported throughout the summer months. Moths are golden yellow in color and approximately 1/2 inch in length. Eggs are laid by females along the midrib or other veins on the undersides of host plant leaves. Eggs hatch and larvae enter the leaf directly beneath the egg shell. The initial mine they create is linear and cannot be seen from the top of the leaf. Larvae range in color from white to pale yellow to green. Second instar larvae are larger, and thus create larger mined areas that coalesce into a blotch shape. Sometimes the larvae breach each other's mines, in which case you can end up with several of them in a single mined area. The final instar larva will emerge from the mine, fold and skeletonize their leaf, and form a thin white cocoon within the fold. Lilac leafminers overwinter either as older larvae or pupae in dropped leaves. In the northernmost part of their range, the larvae will overwinter at the soil surface beneath the leaf litter. Several generations of this species may occur per year. 

Damage to Host: 

This caterpillar creates a blotch type mine on lilac and privet. Early mines are only detectable from the leaf underside. In heavy populations, unsightly and browned leaves may drop prematurely. Typically, only a few leaves are impacted and can be managed with non-chemical options.


In the spring, visual inspection of the underside of host plant leaves is necessary to look for the initial, small, linear and brown mines. 

Cultural Management: 

Pinch or remove and destroy infested leaves to kill the mining larvae throughout the season. At the end of the season, sanitation measures have been suggested by some (to rake and remove leaves where larvae or pupae may be overwintering).

Natural Enemies & Biological Control: 

Little is known about the specifics of the parasitoids affecting lilac leafminer populations, however reports indicate that they do exist. 

Chemical Management: 

Abamectin (NL)

Acephate (NL)

Azadirachtin (NL)

Bifenthrin (NL)

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)


Neem oil (NL)

Permethrin (L)

Pyrethrin+sulfur (NL)

Spinosad (NL)


Products including the above active ingredients may be labeled for use against leafminers.

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.

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: .