Pest profile

Columbine Leafminers

Phytomyza species (e.g., Phytomyza aquilegivora and P. minuscula) · Diptera: Agromyzidae[3]

Columbine leafminers are tiny native flies whose maggots tunnel inside columbine leaves, leaving whitish squiggly trails or blotches that ruin the foliage's looks but rarely harm the plant.[1][2]

Columbine leaf with white serpentine leafminer trails
Columbine leaf with white serpentine leafminer trails. (c) Rose Zappa, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Mines are light gray to whitish serpentine trails or blotches, most visible on the upper leaf surface, widening as the maggot grows.[1][2]
  • Adults are tiny, dark flies, about the size of an eye gnat, that gardeners rarely notice; small punctures in the leaves show where females feed.[1][2]
  • When done feeding, the maggot cuts a crescent-shaped hole and pupates in a small, seedlike, shiny brown puparium on the underside of the leaf.[1][2]

Where it lives

Wisconsin notes several species: P. aquilegivora in the Midwest, a blotch-mining species in the East and P. columbinae in the West; NC State reports them as very common in North Carolina gardens.[1][2]

US map: public records from 26 states since 1990 (GBIF).

Biology and life cycle

Females lay eggs in the leaves in spring about the time columbines start to flower, and maggots tunnel between the upper and lower leaf surfaces.[1][2]

A new generation of flies emerges about two weeks after pupation; NC State reports up to five generations from May to September, Wisconsin up to three.[1][2]

They overwinter as pupae in the soil or in their puparia.[1][2]

Damage and signs

  • Damage is usually only cosmetic; sometimes every leaf on a clump is mined, and NC State notes it is less severe in sun than shade.[1][2]
  • Hybrid columbines are especially affected; Wisconsin suggests the native Aquilegia canadensis, which is usually less damaged.[2]

Health risk

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

Control

Traps and physical control

Pick off and destroy mined leaves as early as possible, before the maggots pupate.[2]

Biological control

Many tiny parasitic wasps attack leafminers, and populations often collapse without pesticides, though usually too late to prevent the damage.[1][2]

Pesticides

If treating, act when adult punctures first appear; once maggots are inside the leaves, sprays can't reach them. NC State reports good results with an imidacloprid soil drench in early spring.[1][2]

Common questions

What are the white squiggly lines on my columbine leaves?
Trails made by columbine leafminer maggots tunneling inside the leaf.[1][2]
Do columbine leafminers hurt the plant?
Usually not; the damage is mostly cosmetic.[2]
How do I get rid of columbine leafminers?
Pick off mined leaves early, before the maggots pupate; sprays don't reach maggots already inside the leaf.[2]

Sources

  1. NC State Extension, “Columbine Leafminer.” content.ces.ncsu.edu/columbine-leafminers-1 (accessed 2026-10-15)
  2. University of Wisconsin-Madison Extension (Wisconsin Horticulture), “Common Columbine Pests: Columbine Leafminer and Columbine Sawfly.” hort.extension.wisc.edu/articles/common-columbine-pests-columbine-leafminer-and-columbine-sawfly/ (accessed 2026-10-15)
  3. iNaturalist, “Phytomyza aquilegivora taxon page (order and family).” www.inaturalist.org/taxa/499395 (accessed 2026-10-06)

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