What's eating my brussels sprouts?

Brussels sprouts attract the full brassica pest lineup — cabbage white caterpillars, mealy cabbage aphids, cabbage root fly, and cabbage whitefly. Because plants grow slowly over many months, pest pressure accumulates. Caterpillars and aphids are the most damaging; fine-mesh covers from transplanting and regular inspection underneath leaves are essential defenses.

Large-white caterpillars shred outer leaves and bore into forming sprouts; frass contaminates the crop. Inspect and hand-pick weekly; apply Bt sprays targeting young caterpillars; net plants with fine mesh to exclude butterflies.

Dense waxy gray-green colonies deep in the plant, curling leaves and stunting sprout development. Apply insecticidal soap or neem oil; introduce parasitic wasps; remove leaves with established colonies promptly.

Root tunneling causes young plants to wilt and fail to establish; transplants are especially vulnerable. Fit brassica collars at transplanting; use fleece row covers; rotate crops to a different bed each year.

White moth-like adults and nymphs on the undersides of leaves; sticky honeydew and sooty mold. Spray with insecticidal soap; introduce parasitoid Encarsia formosa in protected growing; remove affected leaves in autumn.