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Harlequins a threat to horticulture

Infestations of Harlequin ladybirds in the Gisborne district could pose a threat to the horticulture and viticulture industries.

From Asia, the invasive species was first reported to the Ministry of Primary Industries in Auckland in 2016 and has since been found in the Waikato, Bay of Plenty and Taranaki regions.

It has been discovered at Te Karaka and in the Matokitoki Valley.

Harlequin ladybirds are a potential threat to the horticulture industry.

They feed on pip fruit, causing blemishes on the fruit.

They are known to cluster within bunches of grapes before harvest, resulting in tainted juice.

Harlequin Ladybirds also pose a nuisance to humans. They swarm in buildings and houses. They can bite and cause allergic rhinoconjunctivitis.

They eat other insect species and compete for food resources, posing a risk to the biodiversity of the ecosystem. They will eat native ladybirds and also swarm in beehives over winter, requiring manual removal.

Due to their highly variable nature, they can be hard to distinguish from other ladybird species.

The M shaped markings between the head and abdomen, and two small bumps on the rear of the back, are their identifying features. They are also slightly larger than common ladybirds.

The larvae and pupae have a spikier skin than common spotted ladybirds.

If you find a Harlequin ladybird, collect the specimen, photograph it and contact MPI’s free 24-hour pest and disease hotline on 0800 809 966.MPI is tracking their spread and can provide information to growers about the insect and its management.

Two examples of the Harlequin ladybird (left and right) and a pupa (middle). The harlequin is large by ladybird standards — five to eight millimetres long and 4 to 6.5mm wide. It is well known for its variable colouration and patterning, which makes it difficult to distinguish from other ladybird species. It looks similar to the common spotted ladybird. The harlequin ladybird usually has M-shaped makings on the pronotum (the area between the head and abdomen), although this pattern is not present with darker specimens. In contrast, the pronotum of the common spotted ladybird features a W-shaped black mark or two separate U-shaped patches. The harlequin also has small bumps on the rear of its back. Harlequin larvae and pupae have a spikier skin than the common spotted ladybird. Picture by John McLean