Here’s my Lepidopteran of the Month series. You might choose to follow my ‘butterfly’ tag for other posts in this series. Today, a day late for July, let’s admire the cabbage whites. Admire them? Well, more likely loathe them. For the first time in my series about Lepidoptera, I’m talking about pretty pests.
In Britain, this time of year is the time when every market gardener, every amateur vegetable grower, every allotmenteer dreads the sight of white butterflies. We dread white butterflies if we’re growing brassicas – cabbages and their relatives (Brassica oleracea).
Females of both the large white (Pieris brassicae) and the small white (Pieris rapae) oviposit (lay eggs) on brassica plants so that when the larvae (caterpillars) hatch out, they’ll be ready to munch the leaves. No problem, say some novice gardeners. Live and let live. But the tune changes when your lovely fresh produce is full of wriggling caterpillars. As a teenager, I was quite traumatised by dissecting each head of home-grown broccoli on my dinner plate to get rid of the green caterpillars.
UK Butterflies offers us a photographic tour of the ‘whites’ family Pieridae. Many of them are really white, with or without markings, but others are yellow. Stephen Cheshire at British Butterflies shows us more photographs of P. brassicae and P. rapae. He also provides lifecycle information, with charts to show when these species fly. Want more photographs? You might take a look at how Butterfly Conservation shows P. brassicae and P. rapae. To find out more you might look at how Learn About Butterflies describes P. brassicae and P. rapae.
It can be difficult to tell the adults of these sister species apart. They fly quite fast. It’s easier when they’re larvae because those are colour-coded. If you find caterpillars marked in yellow and black on your brassicas, they’re P. brassicae. If you find green caterpillars, they’re P. rapae. So my teenage memories of infested broccoli are memories of P. rapae.
To gardeners, neither species is welcome! But the pierids are part of our land. If they became rare, we’d miss them.
[Edit] My fellow blogger Kay at hortographical tells us that not all white butterflies are pests. Another pierid, the green-veined white (Pieris napi) eats only the wild brassicas.