Pest profile

Oak Shothole Leafminer

Japanagromyza viridula (formerly Agromyza viridula) · Diptera: Agromyzidae[3]

The oak shothole leafminer is a tiny native fly whose females puncture oak buds and very young leaves in spring; as the leaves expand, the punctures become round holes, and the maggots make blotch mines that leave ragged holes.[1][2]

Fallen oak leaf with many small round holes left by oak shothole leafminer
Fallen oak leaf with many small round holes left by oak shothole leafminer. Photo: Dawn VanDeman, public domain (CC0), via iNaturalist

How to identify it

  • The first sign is round holes, often symmetrical on both halves of a new oak leaf, growing up to about 3/8 inch as the leaf expands.[1][2]
  • Blotch mines are light green to tan while active and darken once the maggots leave; the dead tissue later drops out, leaving ragged holes.[1]
  • The adults are very small flies that are rarely noticed.[1][2]

Where it lives

It is considered native and is reported throughout the eastern United States from Maine to Georgia; NC State reports it on most oak species in North Carolina.[1][2]

US map: public records from 21 states since 1990 (GBIF).

Biology and life cycle

Females emerge as oak buds open and pierce buds and young leaves with their egg-laying tube to drink the sap, laying an occasional egg.[1][2]

Maggots mine the leaves and, usually by the end of May in North Carolina, drop to the soil to pupate and spend the summer and winter; there is one generation a year.[1][2]

Damage and signs

  • Hosts include black, bur, post, red, scrub, turkey and white oaks and Chinese chestnut.[1][2]
  • The holes and mines stay on the leaves for the rest of the season but are cosmetic.[1]

Health risk

None to people or pets.[1][2]

Control

Biological control

Numerous parasites attack it, and the next year's infestation may not even be noticeable.[1]

Pesticides

Spraying during the growing season won't improve the tree's appearance, since the maggots have usually left by the time damage is noticed; pesticides are probably best avoided.[1]

Common questions

Why do my new oak leaves have round holes in them?
Oak shothole leafminer females puncture the buds in spring, and the punctures enlarge into holes as leaves expand.[1][2]
Should I spray for oak shothole leafminer?
No. By the time damage shows, the maggots are gone, and spraying won't improve the look of the tree.[1]
Will it happen again next year?
Maybe not; parasites often keep the next year's infestation from being noticeable.[1]

Sources

  1. NC State Extension, “Oak Shothole Leafminer (PDIC Factsheet).” content.ces.ncsu.edu/oak-shothole-leafminer (accessed 2026-10-15)
  2. UMass Extension Landscape, Nursery and Urban Forestry Program (Landscape Insect & Mite Guide), “Japanagromyza viridula (Oak Shothole Leafminer).” www.umass.edu/agriculture-food-environment/landscape/publications-resources/insect-mite-guide/japanagromyza-viridula-formerly-agromyza-viridula (accessed 2026-10-15)
  3. iNaturalist, “Japanagromyza viridula taxon page (order and family).” www.inaturalist.org/taxa/501206 (accessed 2026-10-06)

Updated 2026-10-15. Built from sourced records. Spot an error? Tell us.