Back to top

Phytomyza ilicicola

Native holly leafminer damage. Photo: Jim Baker, North Carolina State University, Bugwood.
Scientific Name: 
Phytomyza ilicicola
Common Name: 
Native Holly Leafminer
Growing Degree Days (GDD's): 
192-298 GDD’s; 350–500 GDD's (adult emergence by mid-May); 1029-1266 GDD's, Base 50F, March 1st Start Date (Source: Cornell Cooperative Extension; Robert Childs, UMass Extension.)
Host Plant(s) Common Name (Scientific Name): 
American holly (Ilex opaca) *Preferred host. Completes development on it and its cultivars.
English holly (Ilex aquifolium) (Johnson and Lyon, 1991)
Japanese holly (Ilex crenata) (Johnson and Lyon, 1991)
Insect Description: 

Seven species of leaf miners feed on holly. Phytomyza ilicicola is usually referred to as the native holly leafminer. This species is known to feed on Ilex opacaI. crenata, and related cultivars; however, it only lays its eggs in American holly (Ilex opaca). Some research suggests that the native holly leafminer may lay its eggs in other Ilex species, but that the larvae are unable to complete their development. This insect is found throughout the native range of its host plants. Larvae overwinter in leaf mines and pupation occurs in March and April and adult emergence by mid-May. Adult flies are known to emerge over a period of 6 or so weeks in the spring. Adults appear by June in Massachusetts. Adults are black and 1.0-1.6 mm long. Females lay eggs using their ovipositor on the underside of newly formed leaves. A tiny green blister forms on the leaf as the first symptom of injury. Larvae hatch from the egg and create a narrow mine that may appear brown from the upper leaf surface. Mines are broadened in the fall and a large blotch is completed in the winter. Larvae are yellow maggots and reach 1.5 mm. in length when mature. Up to 12 larvae may be found in a single leaf. Current year’s mines are easily overlooked due to the slow feeding patterns of the larvae. Phytomyza ilicis is a similar species and usually only referred to as the holly leafminer, and it is a non-native species introduced from Europe and only feeds on Ilex aquifolium. (The native holly leaf miner does not develop in I. aquifolium.) The biology and damage this insect causes is similar to that of the native holly leafminer, with the exception of the fact that eggs are laid in the midvein of the leaf and young larvae tunnel in the vein until the fall.

Damage to Host: 

Foliage of American holly (Ilex opaca) and its cultivars is utilized by this insect. Sometimes reported on English holly (Ilex aquifolium), however the native holly leaf miner may not complete its development there (larvae will not create mines). Mines may appear as yellow and serpentine or blotch-like on American holly. Heavily mined foliage may drop prematurely. Females also damage host plant leaves by puncturing holes in them with their ovipositors. This causes leaf fluids to leak from the hole, on which the male and female flies feed. Some leaves may be so heavily punctured that they become distorted and stunted. Host plants with a heavy population of leaf miners may be thin crowned, with every single leaf mined. 


Monitor for adult flies with yellow sticky cards. Adult flies are tiny and black. This may help with the timing of certain chemical management options. Visually search for leaf mines on susceptible host plants. May not be noticeable until the following season (current season's mines may be easily overlooked). 

Cultural Management: 

Remove and destroy mined leaves before May or before adult emergence begins. This includes raking up and removing any dropped leaves. This may help reduce a population of native holly leaf miners in an individual planting.

Natural Enemies & Biological Control: 

A braconid parasitoid wasp (Opius striativentris) is capable of parasitizing 3-58% of the native holly leaf miner in a single host plant (Potter, 1985). Make chemical management decisions with natural enemies in mind, selecting reduced risk insecticide options to preserve their populations.

Chemical Management: 

Abamectin (NL)

Acephate (NL)

Acetamiprid (L)

Azadirachtin (NL)

Bifenthrin (NL)

Carbaryl (L)

Clothianidin (NL)

Cyantraniliprole (NL)

Cyromazine (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)


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: .