Here’s a valuable lesson taught by Nature in 2019 which was given by caterpillars and concerned the management of stinging nettles.
Nettles have long been appreciated as a favourite larval food plant of three of the most common butterflies – peacock, red a
dmiral and small tortoiseshell, but not much thought is given to its best management for biodiversity.
Currently in the walled garden there are lots of nettle patches, some large and some small. As would be expected, the small clumps are in areas of grass that are cut infrequently, which leads to a decent amount of regrowth between cuts.
In early to mid-July, lots of clusters of caterpillars of all three species named above were seen on many of the small, short-growth clumps and were the second brood of the year.
The implications of this were not understood immediately, but when the realisation came it was clear; eggs would be laid on younger growth purely because it’s softer, so it’s an easier meal for the caterpillars than older, tougher growth. Therefore, any nettles retained as caterpillar food should be cut to ground level towards the end of June. This should be late enough to avoid the first brood of the year that may have fed on them, yet still give time for sufficient regrowth to provide for the second brood.
By managing nettles in this way it will provide better quality food for caterpillars, which may lead to an increase in the populations of adults.
As is often the case, the simplest things can be the most effective. Thank you Nature for showing the way.