Cutworm (Agrotis spp.)
These are the caterpillars, 20-50mm long, of two species of noctuid moth - Agrotis ypsilon (greasy cutworm) and Agrotis segetum (turnip moth) which attack the stems of seedlings and young plants at ground level at night.
Females lay the eggs on all parts of the plant. A fortnight later, the caterpillars emerge, feeding on the leaves for a fortnight before moving into the surface layer of the soil. They feed here for a month or two before pupating in the soil to emerge as moths a fortnight later.
They are more common in dry, light soil and can be seen in the soil around the plants at night and can be recognised by the way they bend into a crescent ('C') shape when disturbed.
- Sudden wilting through partial damage or even complete severing of the stem at soil level.
Prevention & control
- Young plants are less vulnerable than seedlings so avoid direct sowing if badly affected
- Encourage predatory insects through mulching
- Where it is a known problem, sow more seedlings than you need to allow for losses
- Pick them off plants or from the soil at night - search around the base of newly toppled seedlings
- Turn the soil over well after cropping to expose caterpillars and pupae to predatory birds
- Young plants can also be protected by collars - old loo rolls, tin cans with both ends removed, section of drainpipe, etc. - which are sunk a few cm into the soil.
- Pyrethrum, chilli or garlic spray can also be effective