Pest profile

Locust Leafminer

Odontota dorsalis · Coleoptera: Chrysomelidae[3]

The locust leafminer is a small, flat orange-and-black beetle whose larvae tunnel inside black locust leaves, turning trees brown and scorched-looking by midsummer; trees rarely die.[1][2]

Locust leafminer beetle on a leaf, flat and orange with a black stripe down its back
Locust leafminer beetle on a leaf, flat and orange with a black stripe down its back. (c) Nash Turley, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adults are flat, elongate beetles about 1/4 inch long with a black head and orange wing covers bearing a broad black stripe down the center.[1][2]
  • The wing covers are deeply pitted with three long ridges each.[1]
  • Larvae are flat and creamy yellow, slightly longer than adults, and live inside translucent mines that turn brown.[1][2]

Where it lives

Outbreaks occur almost every year throughout the range of black locust, including the Carolinas.[1][2]

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

Biology and life cycle

Adults overwinter in bark crevices and leaf litter and emerge in spring as leaves unfold to feed on leaf undersides and lay eggs.[1][2]

Eggs are laid in overlapping groups of three to five cemented with excrement; larvae mine between the leaf surfaces and may mine several leaflets.[1][2]

Larvae pupate in their mines and new adults appear in July; there are two generations a year.[1][2]

Damage and signs

  • Black locust is preferred; honey locust, apple, beech, birch, cherry, elm, oak and hawthorn are occasionally attacked.[1][2]
  • Damaged trees look frost- or drought-scorched, and whole stands can turn brown by midsummer; outbreaks seldom hit the same trees for more than a couple of years.[1][2]
  • Severely defoliated trees under other stresses may die, but infested trees rarely die.[1][2]

Health risk

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

Control

Prevention

Water a valued locust during summer to help it withstand defoliation.[2]

Biological control

Several parasites and predators attack it, which may be why populations don't stay high in one area for long.[1]

Pesticides

For landscape trees, spray in late May or early June while adults are active and mines are under 1/4 inch long; a product with systemic activity works best.[1]

Common questions

Why are the locust trees along the road brown in July?
Usually locust leafminer larvae have mined the leaves.[1][2]
Will my black locust die?
Rarely; damage looks alarming, but infested trees usually recover, especially with summer watering.[2]
When should locust leafminer be treated?
In late May or early June, while mines are still small.[1]

Sources

  1. NC State Extension, “Locust Leafminer (PDIC Factsheet).” content.ces.ncsu.edu/locust-leafminer-1 (accessed 2026-10-15)
  2. Clemson Cooperative Extension, Home & Garden Information Center, “Locust Leafminer (Jul 12, 2021).” hgic.clemson.edu/locust-leafminer/ (accessed 2026-10-15)
  3. iNaturalist, “Odontota dorsalis taxon page (order and family).” www.inaturalist.org/taxa/132416 (accessed 2026-10-06)

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