NC State Extension Publications

Description and Biology

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Columbine leafminers, Phytomyza miniscula, are very common pests of columbine in gardens. The tiny brown to black flies lay their eggs in the leaves from the underside and their maggots tunnel through the leaves as they grow. Sometimes every leaf of every clump may be disfigured by the leafminers. When the maggots finish feeding, they cut a crescent shaped hole in the leaf and pupate outside in a small seed-like capsule called the puparium. In about two weeks another generation of leafminer flies emerges to repeat the "wheel of existence." Up to five generations occur from May to September. This pest overwinters as pupae inside their puparia.

An adult Columbine leafminer fly and her oviposition punctures on a columbine leaf.

Columbine leafminer flies are about the size of an eye gnat.

Photo by Whitney Cranshaw, Colorado State Univ.,

Columbine leaves typically infested with columbine leafminers

Columbine leafminers often ruin the appearance of columbine foliage.

Host Plants

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John Shread (1968) said it best, "The columbine leaf miner (Phytomyza minuscula) is a pest of columbine and aster. It is much less destructive in sunny exposures than in shaded ones. Early spring foliage becomes infested by adults that emerge from overwintered pupae. As the season advances a great deal of the foliage on badly infested plants may have light grayish to whitish serpentine mines which are most conspicuous in the upper surface of the leaves . . ."

Residential Recommendation

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Leafminer flies have a number of parasites, and their populations often collapse if no pesticides are applied. However, this natural control usually happens too late to prevent unacceptable aesthetic damage. Orthene or imidacloprid should give adequate control of the columbine leafminer. However, the appearance of the infested plants will not improve until new growth emerges to obscure the earlier damage. Orthene and imidacloprid are readily available in most hardware stores and garden centers. We have had good results using imidacloprid as a soil drench early in the spring.


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For assistance with a specific problem, contact your local N.C. Cooperative Extension Center.

This Factsheet has not been peer reviewed.


Professor Emeritus
Entomology and Plant Pathology

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Publication date: Dec. 21, 2013
Revised: Nov. 3, 2023

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