Harlequin Ladybird (Harmonia axyridis)

Dear Readers, I was sitting in the office upstairs, slaving away over my first Open University assignment, when I noticed something red zipping past the window. And then another ‘something red’. And then another. Eventually one of the ‘red somethings’ landed on the window, and I could see that it was a Harlequin Ladybird (it was much too big to be any other species). It packed its wings away, wandered about for a bit and then sat still, probably basking in the sun. After a few moments it was joined by another Harlequin Ladybird, and then another. 

What the hecky-decky was going on? It was a warm day with a light breeze, but I have never seen so many ladybirds on the wing at once. They continued to zip past for a couple of hours, but of course by the time I detached myself from my speciation calculations, there was not a single one to be seen.

Harlequins are fast becoming the most common ladybirds in the UK – they and their larvae are voracious eaters of aphids, and so I often find them, and their black spikey larvae, on the Buddleia. It used to be thought that they ate other ladybirds, but in fact they just outcompete them, which is almost as bad. Still, they’re here now – the first one was spotted in 2004, and twenty years later, here we are. This species comes originally from Asia, was introduced to North America to perform aphid control in the 1980s and was then introduced into mainland Europe, also for aphid control. Chances are that the first Harlequins just travelled across the Channel on a favourable wind.

Harlequin ladybird larvae

But what was happening yesterday? In North America, Harlequins are known as ‘the Halloween Bug’ (not that they’re true bugs but let it pass) because in October they take to the wing to look for places to hibernate. No one knows exactly what triggers it, but my money is on shortening day length and colder temperatures. In the USA there are cases of the ladybirds invading houses in vast numbers, and it’s true that they do like to hibernate together to preserve warmth – I found the little cluster below in the Ladies’ toilet at St Pancras and Islington Cemetery.

When a ladybird finds a good spot to hibernate, it produces a pheromone that attracts other ladybirds. Even when there are no other ladybirds present, a previous hibernation spot will retain some chemicals that tell the ladybird that this is a good place. A ladybird flying through the air will pick out light-coloured structures that are distinct from their surroundings, which means that they often find a building (that will be due to the Grand Designs penchant for white render, I’m sure). So I wonder when all of ‘my’ ladybirds were headed off to. If you suddenly find an aggregation of slightly irritated Harlequin Ladybirds in your shed or attic, do let me know! And be a little bit careful, as Harlequins can definitely give you a nip if they feel threatened.

So, Harlequins do a good job on my Buddleia aphids, but don’t leave much for lacewings/hoverfly larvae/other ladybird species. Yet again we’ve messed up. Still, these are very attractive insects, with a wide-range of colours and ‘designs’. One way to tell if you’ve got a Harlequin is to look for two small dents at the ‘bottom’ of the wing cases, plus a Harlequin is so much bigger than our native ladybirds. Let me know if you’ve spotted any lately, or have seen any on the wing. I wonder if this is just East Finchley, or a country-wide (even worldwide) movement?

Variations in Harlequin Ladybird colouration (Photo By ©entomart  Attribution, https://commons.wikimedia.org/w/index.php?curid=815107)