Information on the Harlequin ladybird taken from The Harlequin Ladybird Survey
The Harlequin – a threat to Irish natives?
What is it?
The harlequin is a large black-spotted reddish or orange ladybird native to south-east Asia, including eastern China and Japan.
Harlequins have been introduced to other parts of the world including Europe to control pest greenfly, mainly in glasshouses.
Why is it a threat?
Unfortunately, harlequins have shown an ability to escape and naturalise in new countries. In Europe, North America and elsewhere wild populations have appeared and spread extremely rapidly.
A by-product of their enormous success has been a decline in native ladybirds and many native species in North America have been decimated as a result of harlequin competition. Not only do harlequins eat their food, but in hard years will also eat the larvae of other species.
Harlequins have recently spread to Britain from the Continent and are expected to reach Ireland within the next few years with an obvious threat to our native ladybirds.
This web page explains the problems that can arise with harlequins and shows you how to recognise them.
How to recognise a harlequin
The harlequin ladybird (Harmonia axyridis) is also known as the Multicoloured Asian Ladybird and the Halloween Ladybird. It has a very variable appearance!
- Size and shape : large (5-8 mm or about 1/4 inch), round
- Elytra (wing case) ground colour: pale yellow-orange, orange-red, red or black; highly variable
- Elytra pattern: many large spots (or none); 0-21 orange-red or black spots, or grid pattern; highly variable
- Most common forms in UK : orange with 15-21 black spots: black with two or four orange or red spots
- Pronotum pattern: white or cream with up to 5 spots or fused lateral spots forming 2 curved lines, M-shaped mark or solid trapezoid
Other characteristics: elytra with wide keel at base; legs almost always brown
If you encounter a beetle which might be this species please note the locality from an OS map and report the details, with a specimen or specimens to: CEDaR at the Ulster Museum (Damian McFerran, CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Holywood, Co. Down, BT18 0EU) or to the author of this article by e-mail
Detailed history of the harlequin
The harlequin ladybird Harmonia axyridis Pallas is an arboreal ladybird native to northern and eastern Asia which has been imported to the United States repeatedly from about 1916 on. It established successfully in SE USA about 25 years ago extending north into Canada and then throughout the rest of the USA. It is now the most abundant ladybird in N. America to the detriment of many native species. Despite the American experience, the animal was also released into Italy and elsewhere in Europe. It has now established and become common in Germany (2000), Holland (2002) and Belgium (2002). Numbers in The Netherlands and Belgium increased greatly in June-July 2004 (despite it being a 'bad' year for aphids and ladybirds).
Not unexpectedly, it reached Britain in September 2004 and had spread by June 2005 to most of the southern counties with reports from as far north as Lancashire (see Map, above).
It is expected to continue pushing northwards and may reach Ireland within the next two to three years.
So, what is the problem?
The reason for the original and all subsequent introductions is a perception that it is a very efficient biological control organism, particularly with respect to aphid infestations of food crops. However, highly invasive behaviour and a very wide dietary and ecological range allow it to potentially eat all the aphids in an area, out-competing native ladybirds whose populations decline by starvation. Some formerly common species in Canada are now rare. When the aphid supply fails, it will predate other invertebrates - hoverflies, lacewings, butterflies thrips etc.. Many of these are beneficial to agriculture, but are put at risk. This scenario has been experienced in N. America and is under way in Europe. The already serious problems caused by harlequin naturalisation on a continental scale could be magnified on small islands such as Britain and Ireland.
The first British record was that of Ian Wright who found a single specimen in the grounds of the White Lion at Sible Hedingham, north Essex on 19th September 2004. It then was then reported from other parts of greater London and the south-east and, despite a flood of mistaken claims and mis-identifications, a substantial number of verified records are now available for the whole of south-east England with a scatter of outliers as far west as Devon and as far north as Lancashire.
It is believed that females overwinter in protected sites unmated, with the majority of the population mating later in the spring. Eggs generally hatch in 3 to 5 days. The larval stage lasts 12 to 14 days, and the pupal stage, which takes place on leaves, lasts 5 to 6 days. In cool spring weather, development from egg to adult can take 36 days or longer. After emergence, adults can live as long as 2 to 3 years under optimal conditions.
In Japan, Harmonia axyridis is primarily a forest species and is common on various aphid-infested trees and bushes such as maple, walnut, willow, and rose; it is also an important predator of various destructive scales in Japan and mainland China. An adult is capable of consuming 90 to 270 aphids per day, and each larva can consume 600 to 1,200 aphids during its development.
Periodic large, and even explosive, population increases are probably caused by the availability and abundance of prey (predominantly aphids and scales), inability of native ladybirds to compete, and lack of natural enemies. It has been postulated that in affected areas the population will eventually fall back to lower, more balanced, levels as prey decreases and natural enemies increase. This should not be relied upon, however, and some assistance in the form of artificially introduced parasitoids or predators may be necessary to stem the tide of damage to native species of ladybird.
A particular problem in the U.S. has been mass hibernation of the adults in and around houses where they constitute a considerable nuisance. In many areas it is recommended that ladybirds be prevented access to buildings by judicious sealing of cracks and openings around windows, doors, siding, and utility pipes with silicone rubber or similar sealant. Interior temperatures in houses often promote continuous activity and since up to 20,000 may occur in any one locality, the problems are obvious. When alarmed, ladybirds discharge a yellow fluid due to reflex bleeding from the leg joints that will stain walls, paint, and fabrics, and that has an unpleasant odour. Rough handling, including vacuuming, is therefore not recommended for disposal and prevention seems to be much better than attempting to remove them once established!