What's eating my flat-leaf parsley?

Flat-leaf parsley (an Apiaceae herb) is targeted by caterpillars of the black swallowtail butterfly, aphids, carrot fly, and celery fly. The Eastern black swallowtail caterpillar is the most dramatic visitor — striking but capable of rapid defoliation. Most infestations are manageable with hand-picking and row covers.

Large, bright green and black-banded caterpillars consume entire stems and leaves, defoliating plants quickly when numbers are high. Hand-pick and relocate (these are valued pollinators). Apply Bt (Bacillus thuringiensis) if damage is severe and you cannot relocate them.

Pale green clusters on leaf undersides and new growth cause curling, distorted leaves and sticky honeydew residue. Blast off with a jet of water; apply insecticidal soap or neem oil to undersides of leaves every 5–7 days.

Larvae tunnel through roots, leaving rusty scarring; plants wilt and yellow; roots become unmarketable. Cover with fine mesh fleece from sowing. Avoid crushing foliage (releases scent that attracts females). Rotate planting site annually.

Larvae burrow through leaves, producing large pale blotches that dry to brown papery patches, reducing photosynthesis. Remove and destroy affected leaves promptly. Cover plants with insect-proof netting. Good plot hygiene reduces overwintering pupae.