Dear Readers, every year, at about the beginning of September, I have to prune the Buddleia in my front garden. It overhangs the road, so it can be very antisocial, especially when people are trying to socially-distance. This year it has been absolutely inundated with greenfly, poor thing, and the honeydew has attracted late-summer wasps, who have been having a wonderful time – in fact, I waited until after some heavy rain to tackle this job, for fear of the very real risk of being stung. But now it’s done, and what a job it was! For those of you worried about the plant, I can tell you that by the end of the autumn it will already be sprouting again, and by next summer it will probably have new growth about eight feet long. Truly, there are few plants as vigorous as Buddleia davidii.
However, every act of pruning involves dislodging some happy predators. Lacewings flew off, ladybirds took to the wing, and I had to re-home a very splendid orb-web spider who had made a little house for herself in a folded leaf. How cosy she looked! I have popped her, complete with leaf, in amongst the lavender for now, and I have no doubt that she will be constructing a huge web somewhere inconvenient as I write.
But what surprised me most was the sheer number of Harlequin ladybird larvae. One even fell down the back of my neck.
This menacing-looking larva is at least twice as big as other ladybird larvae, and is said to be outcompeting the UK’s native species, though I did also spot adult Seven-spot Ladybirds on the plant. I would hope that there was plenty for everyone this year, but in terms of aphid eradication, the Harlequin Ladybird has our native species beat hands down (which is one reason why it has been deliberately released as a biological control in many countries). In the seventeen days that it spends as a larva, the Adonis ladybird (Hippodamia variegata) eats about 100 aphids, compared with the 370 wolfed down by the hungry Harlequin in only ten days. Alas, in the absence of aphids the Harlequin will eat other ladybird larvae, the larvae of lacewings and hoverflies and even each other. However, even in native ladybird species there can be up to 80% mortality in the first few days after hatching if there are no aphids about, as the little darlings set about eating each other. Nothing in nature is ever straightforward. It seems that the Harlequin is here to stay, hibernating in our houses, patrolling our aphid-ridden Buddleias and even occasionally falling into our clothing. Although it comes in a wide variety of colours, it is much larger than other species, and also has a distinctive ‘dent’ at the base of each of the elytra (wing covers). If you live in the southern UK, or the warmer parts of North America, you will most likely have seen one.
Incidentally, some ladybird larvae have evolved not to eat the aphids themselves, and not even the honeydew that they produce, but the moulds that grow on the honeydew! The larva of the Twenty-four spot Ladybird (Subconccinella vigintiquattuorpunctata) lives on the mould that grows on false oat-grass. I learn something new every day.
So, with the cutting back of the Buddleia there’s a definite sense of autumn on the way. I am planting up some pots of sedum and asters to compensate for the end of summer’s bounty, pulling the weed out of the pond, and starting to rake up the leaves. On Friday, I’m off to buy some bulbs for next spring. What a strange year it’s been, but the routines of the garden remind us that some things, at least, continue as always.
Photo One By ©entomart In case of publication or commercial use, Entomart wishes then to be warned (http://www.entomart.be/contact.html), but this without obligation. Thank you., Attribution, https://commons.wikimedia.org/w/index.php?curid=815107
Photo Two By Gilles San Martin – Subcoccinella vigintiquatuorpunctata first instar larva, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=11002359
Information on Harlequin Ladybirds from Beetles by Richard Jones in the New Naturalist series, highly recommended.