This isn’t one for the squeamish. Not quite ‘Pod People’ – hawthorn would hardly make a comfy bed for them to mature in. It was a beautiful early morning, and I was admiring the roses when I caught site of this large sprawling web between my hawthorn bush and climbing roses. The light was filtering through the neighbour’s cherry tree so I could not quite make out what I was seeing at first. I thought, gosh there must be some big spider in there somewhere. But I could not see the wood for the trees, as they say.
And then I saw a wriggling, teeming mass of squirminess (I don’t even know if that is a word or not?). I was both revolted and fascinated at first. What an earth were they? Never mind that, I needed to get my camera. The first image shows it as how I first saw the web in the partial shade, which is kind of creepy, and I was creeped out at first to be sure. With the others images I upped the ISO a little to get more detail.
At first I though they were Ermine caterpillars/larvae, as they form masses of silken webs on vegetation. Yet they didn’t look like caterpillars of any moth. I discovered they are actually Social Pear Sawfly (Neurotoma saltuum) larvae, which not only feed on pear, but also apple and hawthorn and cotoneaster, amongst other trees and shrubs. The web must protect them from predation, for wherever they go the web is there with them.
They appear to be stripping the leaves off the bush within the webbing. Since these photos were taken a few days ago the mass has split into two opposing groups going in opposite directions on the bush. Despite their rampant appetite, the trees are not usually permanently harmed. The larvae will reach a length of 25mm (1in) when fully grown, and then they will go down into the soil to pupate. In the following spring the black coloured adult sawflies will emerge.
Click once to expand view, click again to get that little bit closer
July 2018, rear garden, Staffordshire, England. © Pete Hillman.