The Harlequin ladybird (Harmonia axyridis) arrived in Britain in 2004 after being introduced to USA in 1988. They are present quite widely in the south east of England and are gradually spreading north. Although this non native species could pose a serious problem to British species such as the two or seven spot ladybirds they do not present a public health threat.
Facts about harlequin ladybirds
Also known as the Asian multicoloured ladybird, the harlequin has a very variable appearance. In Britain the commonest form is orange with 15-21 black spots or black with two or four orange or red spots. These ladybirds have 4 distinct life stages: egg, larva, pupa and adult. The adults lay eggs on host plants in early spring. The eggs hatch in 3 to 5 days and the larva stage lasts 12 to 14 days. The pupa stage which usually take place on leaves of fruit trees or plants lasts 5 to 6 days. The adult may live for two to three years and can lay over 1,000 eggs which may account for why the Harlequin ladybird occurs in such vast numbers. Harlequin ladybirds feed on aphids in orchards but also feed of the larva of butterflies and moths and other ladybirds. They can also feed on fruit juices provided by orchard fruit, grapes, pollen nectar and honeydew.
More information about harlequin ladybirds.
How do they affect me?
This invasive non-native species of ladybird has the potential to seriously affect many of the native British species such as the two spot or seven spot ladybirds.
However Harlequin ladybirds chiefly eat aphids they are a potential benefit to gardener and farmer alike. They are not harmful to humans, pets or property, they do not carry disease, they are not poisonous and they don't breed indoors. If squashed, or as a defence mechanism, they release an unpleasant acrid smelling yellow fluid (reflex blood). This is part of the ladybirds' defence mechanism to deter would-be predators but it can also stain soft furnishing. The Harlequin ladybird is more likely to bite than other species of ladybird, especially when woken from dormancy by central heating. They are not considered a public health risk.
How do you control them?
You should fill any small gaps or cracks around doorframes and fit a fine mesh to airbricks. This will help keep the ladybirds from entering your home.
Wipe down the area where ladybirds have been (window sills, door frames etc) with water and mild detergent. Ladybirds leave chemical traces (pheromones) where they have been in order to attract other ladybirds. Regularly washing down these areas will help prevent more ladybirds appearing. Use a fast acting residual spray or general insecticide spray. It is best to use an insect spray before the ladybirds come inside. So spraying in September and October is best. Spray areas such as door frames, window frames and areas where pipes or wires enter your property. The spray acts as a chemical barrier which prevents ladybirds entering. Please be sure to follow the instructions for safe use of any product as shown on the container. Insect spray will be ineffective once ladybirds are indoors (late autumn, winter and early spring). Dead ladybirds can be picked up by vacuum cleaner or dustpan and brush. Do not worry too much about ladybirds in the property, they do not present a health hazard and are likely to leave on their own accord in a few days or weeks. They do no structural harm to the building or its contents.
If you have large numbers of ladybirds in your house, pest control companies will treat for Harlequin ladybirds but are often reluctant to do so as they cannot guarantee their elimination for any length of time and it can be expensive.
We do not treat for Harlequin ladybirds at the present time as they are not considered to be a public health risk.