My hands reek of garlic. I’ve been pulling up invasive Alliaria petiolata, alias garlic mustard. Our resident population of orange tip butterflies lay eggs on it, so we always leave some in one corner of the garden, but if it was all allowed to set seed it would run riot.
Making certain that we only cull plants that haven’t been used by ovipositing butterflies is a slow process. Each needs to be checked for tiny orange eggs or green caterpillars that align themselves along the pods, camouflaged by an almost perfect colour match. Last year, I nearly consigned one to the compost heap, rescuing it in the nick of time.
We kept it in the conservatory, watching it chew relentlessly through garlicky pods; a green eating machine that reached maturity in a few days. It stopped feeding on 25 June 2022 and attached itself to the plant stem with a silken girdle, like the safety sling telephone engineers wear when climbing telegraph poles. Next morning, it had transformed into a sleek, straw-coloured, hard-skinned pupa.
With remarkable developmental foresight, its temporary sarcophagus incorporated a perfectly shaped space for wings that had yet to form, anticipating its own metamorphosis. Unseen, inside, through summer, autumn and winter, the caterpillar’s enzymes digested its body and reassembled the components into a butterfly.
This spring, on 5 April, 284 days later, we found a female orange tip fluttering against the window. We set her free on aubretia flowers. It’s likely that she has laid her own eggs among the plants I’m pulling up today, so I’m taking extra care: this year, it’s personal.
Garlic mustard is very common hereabouts. So are orange tip butterflies. Keeping this garden breeding colony going for almost 40 years hasn’t really been about conservation. It’s a selfish pleasure, revisiting the metamorphosis of a butterfly that I first witnessed as a child: a marvellous annual cycle of renewal that, unlike us, never grows old.
One way of thinking about biodiversity is as an accountancy exercise, a profit and loss spreadsheet. Another is to recognise that there are stories attached to every single species on the planet, there to be discovered. Telling each other those stories is a uniquely human trait.
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