Field Identification
A small leaf beetle whose larvae blotch-mine black locust leaflets—brown windows that make the canopy look drought-struck even when soil is fine. Adults chew elongated holes before the real mining starts.
Upper-surface mines with frass trapped inside; late-season leaves can look scorched. Beetles are dark with a pale stripe—easy to miss until damage scales up.
How to Deal With It
Organic Control Methods
Neem or spinosad on new flush when adults first scar leaves—timing beats volume; oils can smother young larvae if coverage hits mines early.
Parasitic wasps attack leafminer larvae in other systems—preserve them by avoiding calendar sprays; songbirds pick adult beetles where canopies are low.
Accept cosmetic damage on timber/wildlife plantings; do not confuse miner injury with herbicide drift—mines are bounded blotches.
Not practical on tall trees; shear nursery liners and destroy mined foliage if selling clean stock matters.
Scout the first full leaf expansion after bloom—that is when adults RSVP.
Let Nature Handle It
Natural Enemies
- Parasitic Wasps
- Songbirds
Threat Map