Pest identification
What's eating my cos romaine lettuce?
Aphids
Signs: Green or grey colonies on inner heart leaves; honeydew; leaves become sticky and contaminated before harvest.
Control: Inspect hearts regularly; wash off with water; neem oil on outer leaves; grow under fine insect-proof mesh.
Lettuce Root Aphid
Signs: Rapid collapse of otherwise healthy-looking plants; white waxy colonies on roots when dug up.
Control: Annual crop rotation; resistant variety selection; remove affected plants promptly; avoid waterlogged soils that stress roots.
Caterpillars (Cabbage Moth / Angle Shades)
Signs: Ragged holes through outer and mid-leaf; dark pellet droppings; large leaves eaten down to the midrib.
Control: Hand-pick eggs and caterpillars from undersides; Bt spray; fine mesh cover from planting.
Pigeons & Rabbits
Signs: Outer leaves stripped or plants removed entirely; pigeon beak marks tear leaves; rabbits leave clean diagonal cuts.
Control: Bird-proof netting over beds; rabbit barrier fencing 60 cm tall with buried apron; harvest promptly at maturity.
Keep cos romaine lettuce pest-free
Healthy plants resist pests best. Get the basics right:
Cos Romaine Lettuce pests — FAQ
What is eating my cos romaine lettuce?
Cos Romaine's tall, upright leaves are targeted by aphids nesting inside the elongated heart and by caterpillars that chew through the outer foliage. Slugs attack the stem base. The large leaf area makes Cos especially attractive to pigeons and rabbits. Lettuce root aphid can collapse plants from below with no visible warning.
How do I get rid of aphids on cos romaine lettuce?
Green or grey colonies on inner heart leaves; honeydew; leaves become sticky and contaminated before harvest. Inspect hearts regularly; wash off with water; neem oil on outer leaves; grow under fine insect-proof mesh.
How do I get rid of lettuce root aphid on cos romaine lettuce?
Rapid collapse of otherwise healthy-looking plants; white waxy colonies on roots when dug up. Annual crop rotation; resistant variety selection; remove affected plants promptly; avoid waterlogged soils that stress roots.
How do I get rid of caterpillars (cabbage moth / angle shades) on cos romaine lettuce?
Ragged holes through outer and mid-leaf; dark pellet droppings; large leaves eaten down to the midrib. Hand-pick eggs and caterpillars from undersides; Bt spray; fine mesh cover from planting.
How do I get rid of pigeons & rabbits on cos romaine lettuce?
Outer leaves stripped or plants removed entirely; pigeon beak marks tear leaves; rabbits leave clean diagonal cuts. Bird-proof netting over beds; rabbit barrier fencing 60 cm tall with buried apron; harvest promptly at maturity.