No, it is not a case of our ladybirds not eating their aphids but intruder Harlequin ladybirds (Harmonia axyridis). These ladybirds were introduced into North America from Asia in 1988 and some European countries in the 1990′s for biological control of aphids and scale insects.
The picture on the left shows what the Harlequin Ladybird looks like.
You can find a chart here showing our British Native Ladybirds, their sizes and what type of plant they are found on.
Wherever the Harlequin Ladybird appears it is usually followed by a decline of British Native Ladybirds.
Many people now view this species as a nuisance, partly due to their tendency to overwinter indoors and the unpleasant odour and stain left by their bodily fluid when frightened or squashed. They can get into houses through the tiniest gaps, even closed windows. When they wake up they often bite humans when looking for food, this usually causes a bump and stinging sensation but there are documented cases of severe allergic reactions to their bites.
Why should we be concerned:
They have a much longer breeding period than our UK ladybirds and it is feared that they may eat hoverfly, lacewing and our own ladybird larva.
Harlequin ladybirds are very effective aphid predators and have a wider food range and habitat than most other aphid predators (such as the 7-spot ladybird) and so easily out-compete them.
Harlequin ladybirds do not have a requirement for a dormant period before they can reproduce, as some ladybirds have (e.g. 7-spot and eyed ladybirds), and so have a longer reproductive period than most other species. In 2004 in London, harlequin ladybird larvae were found still feeding in late October, long after all the native species had sought overwintering sites.
Read the Harlequin ladybird fact file provided by the Harlequin Ladybird Survey website, which the above was taken from for more information and concerns.
If you find any evidence of Harlequin Ladybirds attacking British Native Ladybirds please send the details to:
‘harlequin-survey (at) ceh (dot) ac (dot) uk’
UK Ladybird Survey on this website you will find lots of information to help you find and identify species, and online forms so that you can record your observations.
Buglife – The Invertebrate Conservation Trust is the first organisation in Europe devoted to the conservation of all invertebrates, actively engaged in saving Britain’s rarest bugs, slugs, snails, bees, wasps, ants, spiders, beetles and many more fascinating little animals.
Nature Detectives award-winning website and wildlife club for under 12s – run by the Woodland Trust.
Ladybirds of Ireland the site dedicated to the study and recording of Irish ladybirds.