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Oak Vein Pocket Gall Midge

Macrodiplosis qoruca (often written M. quercusoruca)[4]

The oak vein pocket gall midge is a tiny fly whose maggots cause pocket-like swellings along the veins of pin oak and other red oak leaves.[1][2][3]

Group
Insect
Order
Diptera
Family
Cecidomyiidae
US records
25 states
Sources
4 cited
Updated
2026-10-17
Underside of an oak leaf with swollen, pocket-like galls along the veins
Underside of an oak leaf with swollen, pocket-like galls along the veins. (c) Nico Carl, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0
On this page
  1. Identification
  2. Where it lives
  3. Biology
  4. Damage and signs
  5. Health risk
  6. Control
  7. Related profiles
  8. Common questions
  9. Sources

How to identify it

  • Look for elongated, pocket-like swellings along the midrib and side veins on the underside of the leaves, which often twist and distort the leaf.[1][2][3]
  • Adults are tiny mosquito-like flies about 3 mm (1/8 inch) long and are rarely noticed.[1][2][3]
  • Each pocket holds a white maggot about 2 mm long.[1][2][3]

Where it lives

Reported on red oaks in North Carolina, Kansas and Oklahoma; in heavy years nearly every leaf on a tree is galled.[1][2][3]

US map: public records from 25 states since 1990 (GBIF).

Biology and life cycle

Females lay eggs in newly unfolding spring leaves; the maggots move to the veins, and gall tissue grows around each within a few days.[1][2][3]

By mid-spring to early summer the grown maggots drop to the ground and stay there until the next spring; there is one generation a year.[1][2][3]

Damage and signs

  • It infests red oaks such as red, southern red, pin and water oak, and is best known on pin oak.[1][2]
  • Heavily galled trees look alarming, but the galls are mostly cosmetic and are often far less noticeable the next year.[1][2]

Health risk

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

Control

Biological control

Parasites, predators and diseases usually bring numbers down by the following year.[1]

Pesticides

Kansas State says there is no control; NC State notes only early spring sprays could work in theory, and most entomologists discourage trying.[1][2]

Common questions

What are the lumpy, swollen veins under my pin oak leaves?
Most likely oak vein pocket galls made by tiny gall midge maggots.[1][2][3]
Should I spray for oak vein pocket gall?
No; there is no practical control, and the galls rarely harm the tree.[1][2]

Sources

  1. NC State Extension, “Oak Vein Pocket Gall Midge (PDIC Factsheet).” content.ces.ncsu.edu/oak-vein-pocket-gall-midge (accessed 2026-10-16)
  2. Kansas State University Research and Extension (Entomology), “Vein Pocket Gall (Kansas Bugs, May 2015, R. Cloyd).” www.k-state.edu/news/kansasbugs/articles/2015/05/vein-pocket-gall.html (accessed 2026-10-16)
  3. Oklahoma State University Extension, “Vein Pocket Gall (Digital Diagnostics).” extension.okstate.edu/programs/digital-diagnostics/insects-and-arthropods/vein-pocket-gall/ (accessed 2026-10-16)
  4. iNaturalist, “Macrodiplosis qoruca taxon page (order and family).” www.inaturalist.org/taxa/714129 (accessed 2026-10-06)

Updated 2026-10-17. Built from sourced records. Spot an error? Tell us.