Caloptilia azaleella

Azalea leafminer damage on host plant leaves. Photo: Tawny Simisky
Scientific Name: 
Caloptilia azaleella
Common Name: 
Azalea Leafminer
Growing Degree Days (GDD's): 
450–800 GDD's (First Generation), 1260–1500 GDD's (Second Generation), Base 50F, March 1st Start Date (Source: Cornell Cooperative Extension.)
Host Plant(s) Common Name (Scientific Name): 
Azalea (Rhododendron spp.) 
Insect Description: 

This moth mines the leaves of its host as a young larva. As the larva grows, it will feed externally on the leaf, rolling the leaf or tying several leaves together as it feeds. Entire leaves are rarely consumed, however aesthetic value may be reduced. Eggs are white and laid one at a time on leaf undersides. Once they hatch, the young larva will enter the leaf and feed by mining. Mines are blister-like and become brown. Dark colored frass (excrement) can be found within the mines. Once large enough (approx. 1/2 inch in length), the larva will exit the leaf and pull it around itself with silk where it will feed by chewing holes. Larvae will select undamaged leaves to roll and pupate inside. A small, golden-yellow adult moth 0.39 inches in length will emerge. There can be 2 generations per year in NY and 4+ in southern states. Overwintering can occur as a late-larva or pupa in a rolled leaf or a small mining larva, depending on climate. Many additional species of leaf rollers, tiers, and miners attack azalea.

Damage to Host: 

Azalea appears to be the only host and is damaged by this insect. Leaves are mined and become brown in patches. Leaves may also be tied together with silken strands as the older larvae feed on the outside of the leaf.

Monitoring: 

Look for brown patches (mines) in the leaves from young larvae or leaves tied together with silk from older individuals. Monitor for rolled leaves indicating pupating moths. Shaking plants in roughly late June-August might result in flying adult moths, a sign that you can use to roughly estimate the population.

Cultural Management: 

Rake up and destroy fallen leaves, which may contain overwintering life stages.

Natural Enemies & Biological Control: 

Parasites do not typically reduce this insect to below-damaging populations.

Chemical Management: 

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 (L)

Horticultural oil (L)

Imidacloprid (L)

Insecticidal soap (NL)

Lambda-cyhalothrin (L)

Malathion (L)

Neem oil (NL)

Permethrin (L)

Pyrethrin+sulfur (NL)

Spinosad (NL)

Tebufenozide (NL)

Notes: 

Mining larvae or larvae curled within leaves will be protected from contact insecticides. 

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).

Gamma-cyhalothrin is labeled for use against adults only.

Chlorantraniliprole and tebufenozide are labeled for use against larva 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: September 27, 2024. To check current product registrations in Massachusetts, please visit the MA Department of Agricultural Resources Pesticide Product Registration page and click on "Search Pesticide Products Registered in Massachusetts - Kelly Solutions".