Harlequin Ladybirds
The Harlequin ladybird Harmonia axyridis arrived in Britain in 2004 after being introduced into the USA in 1988.
They are present quite widely now in South East England and are gradually spreading north. Ladybirds are not regarded as endangered species.
There has been and continues to be a problem with this invasive non-native species of ladybird and they have the potential to seriously affect many of the native British species such as the two spot or seven spot ladybirds.
Frequently Asked Questions
How to recognise Harlequin ladybirds
Also known as the Multicoloured Asian ladybird, the Harlequin ladybird 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.
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Where did the Harlequin ladybird come from?
These ladybirds are native to north-eastern Asia.
They were introduced into North America in the 1980’s to establish them as a biological predators to control aphids and later into parts of Europe.
By 2004 the Harlequin ladybird had arrived in South East England and have spread rapidly, with sightings now in Scotland and Northern Ireland.
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A few facts about the Harlequin Ladybird
Life Cycle
These ladybirds have four distinct life stages: egg, larva, pupa and adult. The adults begin laying eggs on host plants in early spring and hatch in 3 to 5 days. The larval stage lasts 12 to 14 days and the pupal stage which takes place on leaves of e.g. fruit trees/plants, lasts 5 to 6 days. During a cooler spring the process of development from egg to adult may take 36 days or longer. The adult may live for up to two to three years under optimal conditions and a single female can lay over 1,000 eggs, which can account for why the Harlequin Ladybird occurs in such vast numbers!
Feeding habits
The Harlequin ladybirds commonly feed on aphids in orchards but have a wide food range and may also feed on the larvae of butterflies and moths, and other ladybirds. In the absence of insects during the autumn/winter time Harlequin ladybirds can feed on fruit juices produced by orchard fruit, grapes, pollen, nectar and honeydew.
Habitat
Harlequin ladybirds can be found most commonly on deciduous trees such as lime, sycamore and maple but also coniferous woodland. They may also inhabit such plants as nettles, reedbeds and crop systems.
Harlequin ladybirds are also attracted to lighter colours such as white, grey, yellow-coloured houses.
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What these insects do – and don’t do
Because 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 .
In searching for something edible, some may bite us which usually produces a small bump and slight sting.
There are few documented cases of people having a severe allergic reaction to harlequin ladybirds.
The stinging sensation is usually caused by small ‘spurs’ on the ladybirds legs, which prick skin as they move and check whether or not the skin is a food source.
If you have any concern about an allergic reaction – as with any insect bite – contact your GP, NHS Direct on tel: 0845 4647 (24 hour line) or your local A&E Department.
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What should I do if I find Harlequin ladybirds in my house?
Harlequin ladybirds usually find their way into houses (attracted by warm temperatures and lighting) and get trapped there as they try to find a way out or find a protected place to over winter and remain there until spring.
They ladybirds tend to enter wall spaces only and so remain unseen.
They do no structural harm to the building or its contents.
It is only when the ladybirds enter the house through cracks and crevices around doors and windows that they can become a nuisance, especially if there are large numbers of them.
Cooler rooms are less likely to attract the ladybirds.
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What can I do to control them around the house or better still keep them out altogether?
Eliminate points of entry
- Fill any small cracks/holes/gaps around doorframes and window frames and fit a fine metal mesh over airbricks (on the outside and/or the inside of your home) which may help to keep the ladybirds out or prevent them from returning the following autumn/winter, while still maintaining ventilation.
Remove chemical traces
- Wipe down the areas where ladybirds have been with water and mild detergent such as windows, window frames, door frames.
- Ladybirds leave chemical traces (pheromones) where they have been in order to attract other ladybirds.
- Regularly washing down the areas where the ladybirds have been seen, especially from early Spring onwards when the adults emerge from hibernation through to late Autumn.
Use of insect spray
- It is best to use an insecticide BEFORE the ladybirds come indoors - during September and October is best - using a fast acting residual synthetic pyrethroid* spray or a general insecticide spray. (NB *Pyrethroid is the active ingredient).
- Thorough covering is essential. Suggested areas to spray are window and door frames, and areas where pipes and wires come through walls.
- The spray acts as a chemical barrier which serves to prevent the ladybirds from entering.
- Be sure to follow safety instructions for use of the product as shown on the container! i.e. Wash your hands thoroughly after use and avoid using this spray if you suffer from asthma. Do not use the spray near to goldfish and other indoor aquatic creatures.
- If you have very 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. They can kill the ladybirds which are seen wandering around but cannot successfully treat those which are hibernating for reasons already given.
- Insect spray is ineffective once the ladybirds are indoors during the hibernation time (late Autumn, Winter and early Spring) as the insect’s physiological activity is very low and so the insecticide’s chemical ability will be very low due to cooler temperatures.
- NB London Borough of Bexley do no treat for Harlequin ladybirds at the present time as they are not considered to be a Public Health risk.
- Dead ladybirds can picked up by a vacuum cleaner or dustpan and brush/broom.
Vacuuming
- Use a vacuum cleaner with a narrow nozzle attachment to a hose or dustpan and brush/broom to pick up beetles (dead or alive).
- Pay special attention to windows and lighting fixtures as the ladybirds are attracted to light.
Finally…try not to worry unduly, your patience is likely to be rewarded by the ladybirds leaving on their own in a few days or weeks.
For further information:-
A Harlequin ladybird survey is being carried out by the University of Cambridge (part funded by DEFRA) and has a very informative website:-
 http://www.harlequin-survey.org/
The above information was sourced from the above website with permission
WS 14.04.2008
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