Orange Ladybirds are here to stay and that’s good news

Up to 1987 the orange ladybird was considered a specialist species of ancient woodland. Since that time it has been spreading; initially to sycamore trees and later to the ash

I have, this week, two talks to give in the space of three days. By the time you read this, you will have already missed the first; a guided tree walk around the streets of Archway and Highgate Hill. It will be an unusual walk, not least because half of it will be in darkness. Still, needs must, and, to the probable curiosity of local residents, we’ll just have to take torches and see what we can detect. It won’t all be based on chance, however, and it was whilst I was out rehearsing the route that I came across not just interesting trees but also an interesting creature. And, in this case, the torchlight might be a positive advantage.

I have written in these columns before about the spread of the harlequin ladybird and of its possible harmful effects on our native species. It is good, therefore, to be telling a good news story for once, and one about a ladybird to boot. Ladybirds can be confusing in their appearance, with the same species varying in the number of spots and even in the background colour. No such confusion should occur, however, around the identification of the orange ladybird. It is a distinctive yellow-orange colour, reminding me of a home-made lemon curd I was once given, and its spots are a pure white. They are sixteen in number, a fact celebrated in its rather awkward scientific name of halyzia sedecimguttata, though the books tell me there can occasionally be less.

Unusually among our ladybirds it does not, in its adult form at least, feed upon aphids. It is, in fact, largely vegetarian, its favourite food being mildews and moulds. In winter the orange ladybird often gathers in large numbers to hibernate, either in leaf litter or on the protected parts of trees, and this was how I first came across them some years ago; large clumps of the insects piled on top of each other, on the bark of trees in the tiny nature reserve at Barnsbury Wood. This particular ladybird also has the habit of flying at night and is commonly attracted to light, often being caught in moth traps. So this, at least, is where our night time tree-walk torches might come in handy.

But what about that good news I mentioned? Up to 1987 the orange ladybird was considered a specialist species of ancient woodland. Since that time it has been spreading; initially to sycamore trees and later to the ash. It has reached the point where it is now considered ‘common’ or, in some places, even ‘abundant’. I have yet to come across an explanation for this change in status but a little hypothesis of my own is beginning to form. The sooty bark disease of sycamores is another fairly recent introduction, being first detected in this country in 1945. It is caused by a fungus and begins its spread as large patches of chocolate brown or blackish spores appearing under paper thin and peeling layers of bark. It is now becoming common –and was especially so during the hot summers of a few years ago. A serious infection can kill a tree within two years and leaves a dramatically barren trunk, stripped of leaves and bark and covered from top to bottom in a dark brown ‘soot’. Interestingly there was just such a dead tree in Barnsbury Wood when the ladybirds first appeared and, since their spread to sycamores followed closely on the spread of the sooty bark disease, I am tempted to wonder if the ladybirds found a new food source in this form of fungus. It is, of course, pure speculation on my part, with no scientific validation, but still, it’s worth a thought.

But to return to my tree walk; the ladybirds that I found were not on sycamore, nor even on ash, but on a group of exotic street-side birches in Guisbach Road, evidence that their continued expansion is taking them onto ever new species. And that is where I will have been on Tuesday, shining torches up a street tree in Archway, and answering awkward questions from suspicious passers-by.

If you happen to have missed all this excitement, there’s still the chance to catch my second talk of the week. It’s the annual Kate Springett lecture and it takes place tonight ( 25th October) at Hampstead’s Burgh House at 7.30. Entitled ‘From pig keepers to parakeets’ it’s a history of our relationship with the wildlife of Hampstead Heath. Hopefully it will be fully lit. Be there.