The inaugural meeting of the Ivydale Primary School Natural History Club had its first show-and-tell session on Wednesday. The first ladybird of the year had made an appearance.
The inaugural meeting of the Ivydale Primary School Natural History Club had its first show-and-tell session on Wednesday. The first ladybird of the year had made an appearance.It was crawling about in the back bedroom of one of the children and she proudly presented it in her flip-top jewellery box.
It was the harlequin ladybird, Harmonia axiridis. This was a 'new' species, first found in the UK, in Essex, in 2004. It sparked a spate of unhelpful and alarmist news stories about alien invaders wiping out our British ladybirds. The basis for these rumours was the observation that in the USA Harmonia axiridis out-competed native ladybirds, even eating their larvae, leading to some serious declines in local species.
Sure enough, H. axiridis is very large and aggressive, especially its larvae, which are twice the size of our common seven-spot ladybird larvae. But whether the harlequin will do serious ecological damage here remains to be seen. It coexists quite happily with seven-spot ladybirds and two-spot ladybirds in Japan, and since Japan has an oceanic-temperate climate like the UK rather than a continental climate like the USA, maybe the Japanese experience will be repeated here.
The harlequin ladybird has been deliberately transported around the world, and released into the wild well outside of its original Asian homeland. This is because it is a very useful biocontrol agent, attacking the many non-native aphids and other plant lice that have themselves been moved about the globe, albeit accidentally. Ironically, the seven-spot ladybird has also been accused of causing ecological havoc in the USA. It was deliberately released there many times since the 1950s before it finally became established and was still spreading when I found it in Florida in the 1990s.
H. axiridis was released as a biocontrol in the Low Countries, but no one is quite sure how it got to the UK. It could easily have been brought over in horticultural or other goods, or accidentally on cars or other vehicles travelling over from Europe.
This is actually the second Harmonia to arrive 'new' to Britain. The cream-streaked ladybird, H. quadripunctata appeared in the early 1940s, and although it too is a large and obvious beetle, its spread was slower and caused far less alarm. It seems to prefer pine aphids and I only found it in London last year, for the first time.
The harlequin ladybird is all over south London now, and although I saw lots in 2006, they were fewer and further between in 2007. Oh, and the seven- and two-spots were still very much in evidence.
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