The beautiful Peacock is a pleasure to watch in the spring and early summer. It lays its eggs on nettles, of which we have an abundance, and its furry black caterpillars pupate about late July to early August.
There are many others, and if you want to research them, go to www.butterfly-conservation.org
But the above are the butterflies we love – now to the ones we hate – the white ones .
There are two varieties:
The Large white. The Large white’s caterpillars are greenish to yellowish with dark stripes. This caterpillar is a lot easier to spot than the Small white’s. The Large white tends to lay lots of eggs on one plant, so there may be dozens of caterpillars on one unfortunate plant amongst your brassica’s. The Large white is also attracted to nasturtiums, and may prefer to lay its eggs on this food plant. (the leaves and flowers are edible) – but to let them reach the pupal stage is just asking for trouble. When they reach the optimum size they fall to the ground, dig a hole, and pupate, to emerge as second and even third generations in the same year, or overwinter to begin the cycle again. The caterpillars my escape some predation as they resemble the moth larvae that feed on the poisonous ragwort.
The Small white is a trickier customer, it will skip amongst your brassica, laying only one egg at a time (then another will come along, and another etc).
The caterpillars are very difficult to see, as they blend with the brassicas they are feeding on. I suspect they might also be night feeders, and ‘hide’ during the day to foil predators like wasps and birds.
Good gardening, and good luck.