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Insects and other arthropods

Asian lady beetle

English
Harmonia axyridis

Tabs group

Description

Asian lady beetles are between 4.8 and 7.5 mm long. Their elytra, covering a pair of membranous wings, occur in different shades ranging from yellow, orange and red to black and have anywhere from 0 to 20 spots. In Canada, the most common form is orange with 19 black spots.

The pronotum, which covers the front of the thorax just behind the head, has two football-shaped pale eye spots.

Life cycle

Adults leave their shelter in the spring to mate. The eggs are laid on the underside of leaves, often near an aphid colony, for the larvae to feed on. Females produce hundreds of eggs, which hatch three to five days later. Larvae resemble tiny alligators, first light grey then black with yellow, orange or red spots and are covered with spines and tubercles. Larvae moult three times in two weeks. The mature larvae attach themselves to the undersides of leaves and transform into the pupal stage. The last moult takes place one week later, when the adult beetle emerges. Asian lady beetles congregate in October and look for a place to spend the winter.

They produce probably two generations a year in Quebec, maybe three if the summer is long and hot.

Geographic distribution

The Asian lady beetle is native to Japan, China and Korea, among other countries.

It was first successfully introduced to North America in 1988, in Louisiana. Since then, the beetle has spread across the United States and moved into Quebec, establishing itself in the southern part of the province as far as the upper Laurentians.

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