Sun. Jun 16th, 2019

Invasion of the ladybirds! Why are these STI-infected insects taking over our homes? | Environment

2 min read

‘Invasion of cannibal ladybirds carrying STIs wreaks havoc,” screams the Sun. Should we scoff at such sensationalism? Well, the red-tops are mostly correct. Except for the havoc bit.

There are plenty of ladybirds about this autumn and many are flying into our homes. Unlike our native letterbox-red ladybirds, these creatures are often orange or yellow and possessing many spots, or none.

These multi-hued, home-loving ladybirds are harlequins. This Asian species’ voracious appetite was deployed to control aphids on crops in the US in the 1980s. It soon spread to Europe, and arrived in Britain in 2004. The best way to distinguish it from native species is to look for white markings behind the harlequin’s head, and its brown – rather than black – legs.

Such harlequin happenings now occur every autumn, but numbers are greater this year after the UK’s glorious summer, according to the nation’s leading ladybird expert, Professor Helen Roy of the Centre for Ecology & Hydrology.

‘A wildlife spectacle’ … a harlequin ladybird on wild tansy in Wales. Photograph: Alamy

While native ladybirds survive the winter months by hiding in leaf litter outdoors, the harlequin prefers our houses. It is drawn to pale colours – ceilings, for instance – which probably remind it of ancestral rock mountainsides.

But Roy urges us not to kill them. “It is quite a wildlife spectacle,” she says. “They may be a nuisance if someone doesn’t want hundreds in their bedroom but they are not a human health concern and biodiversity concerns are much greater than ‘human nuisance’.” Hoovering up harlequins is also pointless, says Roy, because this “invasive” species is unstoppable. It is here to stay.

As to whether they really carry sexually transmitted infections, “ladybirds have an unfortunate number of STIs”, says Roy, “but they pass them only within themselves”. Scientists get excited about this stuff. Look out for tiny yellow fruiting bodies on a harlequin’s back. “It’s an amazing fungus,” says Roy.

These diseases are not spread to native ladybirds and evidence suggests that native species flee predatory harlequins. The harlequin’s full impact on invertebrate ecosystems is not yet known. In the meantime, the best thing we can do is help scientists log harlequins via the iRecord app or the online ladybird survey and try to live peacefully alongside this vibrant new species.

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