Environment

Alligator weed moth.
Source: Landcare Research Biocontrol agent:
Alligator weed moth

Scientific name:
Arcola (previously Vogtia) malloi

Target weed:
Alligator weed
Alternanthera philoxeroides

What do Alligator weed moths look like?

The adults are 13-14 mm long and are pale brown with large black eyes. They are nocturnal and hide away during the day. 
 

What about their life cycle?

This moth can complete several generations in the warmer months, with the time from egg to adult being as little as 6-7 weeks. Adult females begin egg laying in spring, with the eggs being white, oval and laid singly on the underside of leaves and in the leaf axils near the top of stems.

The caterpillars are a whitish, amber colour and develop brownish stripes along their bodies. They live inside the stems and feed for about a month before pupating inside a sealed off chamber inside the stem. The pupae are initially amber but turn dark brown. The chamber has a small, round membranous window through which the moth emerges about a week later.

Where are they established?

There is patchy distribution in the Dargaville area, but the best collection site is a farm dam on Paerata Road, Tangiteroria.

When and how can they best be harvested for redistribution?

From December to March look for wilted Alligator weed stems. Split these apart to find caterpillars and pupae inside. Collect several paper rubbish bags of wilted stems and spread to new sites.