Halmus chalybeus, commonly known as the steelblue ladybird, is a species of ladybird (the beetle family Coccinellidae). It has a rounded appearance with an iridescent blue/green colouration and is a predator of other insects. It was introduced to New Zealand from Australia in 1899 and 1905 to control black scale and blue gum scale (see scale insect) on citrus trees, where it is now common in northern regions. It has also been recorded eating San Jose scale. They are about 3–4 mm long.