I saw Small Tortoiseshell caterpillars up the Welcombe today

Stingers don't appear to be much use for anything apart from causing pain and discomfort at the slightest touch by bare flesh or through any flimsy garment. Do dock leaves really soothe the painful nettle rash? Believe what you will, children across the generations have been urged to rub the rash with dock leaves and probably still do. Does it really work? The Natural History Museum thought so, but others aren't so sure. The sceptics say the nettle sting is an acid (methanoic or formic) which would take an alkali to neutralise it. Dock contains oxalic acid so can't possibly neutralise it. 

What is for certain is that Peacock, Small Tortoiseshell and Comma butterflies love stingers!

I've posted pics from last year already showing dozens of spiny Peacock larvae over nettles in Rowley Fields. Yesterday morning I was on the lookout for earlier signs of the butterflies' activities by checking nettles for curled-up leaves, see below.

Many will think these leaves are unfurling or even dying back. They actually contain a little secret. The Small Tortoiseshell butterfly lays dense mounds of green eggs on the underside of topmost nettle leaves. When they hatch the caterpillars (larvae) spin a web which protects them. The silk strands contract as they dry pulling  the sides of the leaf together providing added protection.

Carefully opening one up the larva can be seen. This one was on the leaf feeding and dashed back into its web as soon as it felt in danger. It's immature (hence green)  but will soon turn black as it grows and those black dots will form the spines. The other black dots on the nettle leaf are poo. The holes in the leaf show where it has been nibbling.

Nettles are good then and now we know what they are for. These ones were just inside Blue Cap Covert behind the benches in the upper Rowley Field.