Pest identification
What's eating my sweetcorn?
Corn earworm (Helicoverpa zea) — US; European corn borer (Ostrinia nubilalis) — US/UK
Signs: Caterpillars follow silks into the cob tip and devour kernels; entry holes fill with frass; significant yield loss.
Control: Apply Bacillus thuringiensis (Bt) to silks at 10% emergence; repeat every 3–5 days during silk period; mineral oil drops on silks as a barrier.
Birds (crows, pigeons, jackdaws)
Signs: Peck out and uproot newly germinated seedlings; tear open cob husks of ripening cobs.
Control: Sow under cloches or start indoors; net plants or use individual cob bags as cobs form; bird-scarer tape near crop.
Badgers, squirrels & foxes
Signs: Flatten stalks to reach cobs; bite through husks; an entire crop can be lost in a single night.
Control: Electric fence around the patch is the most effective deterrent; cage individual cobs with plastic bottles or paper bags.
Corn leaf aphid (Rhopalosiphum maidis)
Signs: Dense grey-green colonies on tassels and leaves; honeydew promotes sooty mould and can impair pollination.
Control: Tolerate low numbers — natural enemies usually regulate populations; insecticidal soap spray if colonies are dense before tasselling.
Keep sweetcorn pest-free
Healthy plants resist pests best. Get the basics right:
Sweetcorn pests — FAQ
What is eating my sweetcorn?
Sweetcorn is targeted by both insects and wildlife. Corn earworm is the most damaging insect, tunnelling into silks and cobs. Birds pull up seedlings and peck ripe cobs; badgers, squirrels, and foxes raid cobs as they ripen. Aphids build up on tassels. Netting and electric fencing are the most practical defences.
How do I get rid of corn earworm (helicoverpa zea) — us; european corn borer (ostrinia nubilalis) — us/uk on sweetcorn?
Caterpillars follow silks into the cob tip and devour kernels; entry holes fill with frass; significant yield loss. Apply Bacillus thuringiensis (Bt) to silks at 10% emergence; repeat every 3–5 days during silk period; mineral oil drops on silks as a barrier.
How do I get rid of birds (crows, pigeons, jackdaws) on sweetcorn?
Peck out and uproot newly germinated seedlings; tear open cob husks of ripening cobs. Sow under cloches or start indoors; net plants or use individual cob bags as cobs form; bird-scarer tape near crop.
How do I get rid of badgers, squirrels & foxes on sweetcorn?
Flatten stalks to reach cobs; bite through husks; an entire crop can be lost in a single night. Electric fence around the patch is the most effective deterrent; cage individual cobs with plastic bottles or paper bags.
How do I get rid of corn leaf aphid (rhopalosiphum maidis) on sweetcorn?
Dense grey-green colonies on tassels and leaves; honeydew promotes sooty mould and can impair pollination. Tolerate low numbers — natural enemies usually regulate populations; insecticidal soap spray if colonies are dense before tasselling.