Cutworms emerge from beneath the soil in the evenings to feed on the surface. They often cut off young plants by cutting through the stems at ground level.
They are the caterpillars of the Cutworm Moth and primarily do damage in early season as the young plants are tender and easy to eat.
Some cutworms are darker brown.
Some cutworms also climb up the plant and damage leaves and flowers, but most serious damage is done with the cutting off of young plants.
Cutworms can be as long as 5cms, normally dark brown and generally have the 'caterpillar' appearance, though with shorter legs.
They are normally active in UK during mid to late summer. Preferring young plants either in the vegetable or flower garden. Hoeing around plants will normally disturb them and bring the cutworms to the surface. Blackbirds enjoy hunting for cutworms, so should not be deterred from digging about near your plants.
There is no soil insecticide available for cutworm infestation.