Social pear sawfly

I've been looking at these densely woven web cradles for a while, wondering what is going to hatch in them and whether I should be trying to stop them. Now we have wriggly orange caterpillar-like larvae, and I've established that they are social pear sawfly larvae, relatively common across southern England and, according to the RHS, part of the garden's biodiversity and not harmful to the host trees (apart from eating the leaves in their webs). These are on a small, self-sown hawthorn which, in the autumn, we will try to move to the orchard hedge. They also live on medlars and cotoneaster as well as pear trees. 

It was a day of little jobs, including picking some beautiful strawberries and some very plump blackcurrants.