Friend or Foe: The Harlequin Ladybird (Harmonia axyridis)
The Harlequin ladybird made sensational news headlines on 19th September, 2004 when the first sighting of this particular species was recorded at The White Lion pub garden in Sible Hedingham, Essex. Four years later the ‘deadly invader’ is listed by the Royal Horticultural Society as the second biggest garden pest in Britain, behind slugs and snails.
The Harlequin Ladybird
The harlequin is 7mm long, slightly larger than the common 7 spot ladybird and much rounder. The most common species are orange in colour with 15 to 20 spots, although black harlequins with orange spots are not an uncommon variety.
Harlequins were deliberately introduced into North America over 25 years ago from their native Japan as an attractive means of biological aphid control. Today they are the most common ladybird in that continent.
Closer to home mainland European countries also introduced the harlequin and so it is hardly surprising that this beetle made the short hop across the English Channel and arrived undetected by eagle eyed customs officers.
The harlequin is seen as a potential threat to our native species of ladybirds (pictured below)
It is strongly suggested that once the harlequin becomes established in this country many of our rarer species could disappear in the next 10 years. This beetle is thought to be able to out compete our British ladybirds for food. They have a voracious appetite and in North America they prey on aphids, greenflies, hoverflies, whilst in the absence of natural food they prey on butterfly eggs, caterpillars and their larvae and other ladybirds. They are also very partial to soft fruit and are known to affect crops of pears, grapes and strawberries.
Experience in America has found that the harlequin likes to take shelter in buildings during the colder months and swarms have been reported in houses throughout the States. They appear to do no damage to the building structure but leave vile smelling yellow secretions that are hard to get rid of, causing damage to the interior furnishing of homes.
However the jury is still out on the potential threat that the harlequin poses to British ecology and the damage that may be done as its numbers increase. The harlequin has been reported as far a field as Scotland, Wales and Northern Ireland with growing colonies in the south east, where it first established itself. However, alarmists tend to look to the experience of the Americans for predictions of gloom. Whilst it is wise to be cautious it should also be pointed out that parts of America have a different climate from Britain. Japan, the harlequin’s native country shares the same oceanic temperate climate with Britain and their experience is that the harlequin and the 7 spot ladybird can coexist quite happily.
At Oaktree Home and Garden Centre we are actively encouraging native ladybirds to visit the garden by stocking the Ladybird Tower
On 15th March, 2005 a harlequin survey was launched by The University of Cambridge, Anglia Ruskin University, The Biological Records Centre and CEF at The Natural History Museum in London.
This is an ongoing survey and everyone is invited to report their findings. It runs alongside the ladybird survey.
www.harlequin-survey.org
www.ladybird-survey.org
With thanks to Jean for researching and writing the above article.