Country diary: Not every group of ladybirds is a loveliness

·2 min read

As an organic gardener, I’ve become resigned to the fact that by the end of May my broad beans are always besieged by black bean aphids. Then, in June, a generation of winged females seeks out summer host plants, colonising my French and runner beans, nasturtiums and dahlias. But this year, there’s been a curious dearth of the sap-sucking insects. Where I’d normally find them massing on soft shoot tips, stems and the underside of leaves, my plants remain unblemished.

Initially, I thought I had blue tits to thank. A pair nested in my garden for the first time this year and have been busily gathering insects to feed their clamouring chicks. But after staking out the box, I determined that they were primarily providing them with juicy green caterpillars.

It wasn’t until I began harvesting my vegetables that I realised the garden was overrun with harlequin ladybird larvae. I’d previously noticed a few of the alien-looking black and orange creatures prowling the sweet peas and spotted one crawling on the bird bath, but now I find half a dozen nestled among the leaves of every bunch of radishes, and each time I rinse freshly cut salad leaves I have to rescue two or three flailing bodies from the sink. Over the past few weeks, I’ve found the larvae, immobile dome-shaped pupae and glossy-shelled adults on virtually every edible and ornamental plant in the garden.

The collective term for ladybirds is a loveliness, but while the variably patterned adults are undeniably attractive – and they and their offspring have evidently made short work of the aphids – these gardener’s friends are an invasive species and have a less endearing side.

Harlequin larvae have long, ribbed, bumpy exoskeletons, earning them the nickname “insect alligators”, and these tiny predators are just as deadly as their namesake. Though they have a voracious appetite for aphids, consuming up to 100 a day, they also prey on our native ladybird eggs and larvae, as I discovered when I came across a robust harlequin with a half-eaten two-spot clamped in its jaws.

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