Technical Name: Plutella xylostella
General:
Found throughout New Zealand. Adults are nocturnal in habit and the female lays up to 100 light yellow oval eggs usually on the underside of leaves. Larvae cause the most damage by feeding on the leaves with young larvae boring into the leaf and feeding on the internal leaf tissue.
Identification:
Small thin and grey in colour. Has a wingspan of 7-10 mm. Identified by characteristic diamond shaped spots that are visible when the wings are folded along the body. It can be hard to distinguish between diamond back moth larvae and white butterfly caterpillars. Diamond back moth larvae tend to drop off leaves on a thread when disturbed while white butterfly caterpillars tend to rear up and be aggressive.
Image courtesy of Olaf Leillinger