Greenish coloured caterpillars

Greenish coloured caterpillars

Observation - Greenish coloured caterpillars - UK and Ireland. Description: They (lots of them) are on lettuce flower head, just sitting there not feeding. And the plant doesn't have any visible damage either.

They (lots of them) are on lettuce flower head, just "sitting" there not feeding. And the plant doesn't have any visible damage either.