What's eating my betula nigra?

River birch is notably more resistant to bronze birch borer than white-barked birches, making it the safest birch for warm climates. Aphids and sawflies cause seasonal cosmetic damage. Leaf miners occasionally attack but healthy trees tolerate them well. Good watering and mulching keep most pest pressure low.

Large colonies on new shoot growth; sticky honeydew below the canopy; leaves may yellow; sooty mould on coated surfaces beneath Insecticidal soap or neem oil; blast off with a strong water jet; natural predator populations (ladybirds, lacewings) usually control aphids without intervention

Pale blotch mines inside leaves from late spring; leaves brown and drop early, weakening the tree over repeated seasons Remove and destroy fallen leaves; systemic soil drench insecticide for persistent infestations; maintaining tree vigour with adequate water and mulch reduces susceptibility

Skeletonised leaves eaten from the edges; groups of pale green larvae feeding together; defoliation of individual branches in heavy years Hand-pick small colonies; insecticidal soap spray on larvae; Bt is less effective on sawflies — pyrethrin-based spray works where chemical control is needed