Butterflywatch: large white caterpillars thrive on perennial kale

I returned home from a week’s holiday to find my lush patch of perennial kale turned into pale skeletons. Everywhere I looked, large white caterpillars were marching, searching for more leaves. They even devoured my wild rocket.

This is the dreaded “cabbage white” loathed by many gardeners. The caterpillars of the similar-looking small white feed on brassicas too but tend to live singly, and appear to do less damage. And the green-veined white, frequently misnamed as a cabbage white, does not feed on brassicas at all.

I’ve grown perennial kale for 10 years and large whites have often laid eggs on the plants, but the caterpillars have never developed before. I had assumed these tougher perennial leaves were not palatable for hungry caterpillars.

So it is strange that in one of the worst-ever summers for butterflies I’ve fed a burgeoning large white population. But nature tends to find a balance and a huge proportion of these caterpillars have been parasitised by tiny wasps and will never emerge as late-summer butterflies.

Like most insects, butterfly populations frequently plummet and quickly bounce back. The hope is that this year’s apparent bust – caused by relentless rain in the first half of this year but accentuated by the climate crisis, farm chemicals and habitat loss – will be followed by a boom. Here’s to the class of ‘24 – large whites included – bequeathing a bigger generation next year.