The various white butterflies can be difficult to tell apart but the Orange-tips (Anthocharis cardamines) are a little easier to spot. The male sports the orange tips on its wings that give the species its common name and which are, according to the UK Butterflies website, caused by an accumulation of the mustard oils that were ingested when it was a caterpillar.
The female Orange-tip doesn’t have those bright wing tips but she does share with the male the equally characteristic mottled green pattern on her underwings.
The female lays a single egg – the caterpillars will devour other eggs and fellow caterpillars given the chance, hence the single egg – on one of the preferred larval food plants, their favourites being Cuckooflower (Cardamine pratensis) and Garlic Mustard (Alliaria petiolata). Eggs are white when first laid, changing to orange as they near maturity, a process that takes a week or two.
I haven’t yet found a caterpillar but, in the next week or so, I will be re-checking the places where I found these eggs. If you want to read more about Orange-tips, you can check the Butterfly Conservation website here.