THE DEVOURING
VERMILLION-SPOTTED CREATURES
AT ORFORD

It was on my birthday that we decided to take the National Trust ferry across to the bleak and desolate terrain of Orford Ness. Straightaway, it had the feel of ex-military about it, lots of concrete and bizarrely-shaped abandoned installations. However, not far along the red route, we spied tough silken nests of caterpillars on a small, no more than a metre tall, solitary hawthorn shrub. One of these disc-shaped constructions with tenacious silken threads running in all directions was nearly 12cm across and 4cm deep and heaving with dark larval forms, most around 20-25mm long, (photographs on p 16). The morning sun of early May was no doubt activating the denizens of this fine silken creation.

These occupants were simply lovely to watch; they were not in a hurry and were not going to be travelling very far anyway. They were already where they wanted to be – on their food plant! As far as they were concerned, life couldn’t get much better. Being active and growing at the same time as the new ‘soft and nutritious leafy shoots’ of your ‘parent’ plant can only be a lovely coincidence of nature’s wondrous design.

Close up of the main nest

What identified them as Brown-tail caterpillars were a couple of small but very striking vermillion protrusions near the back end of the darkish but very hairy body in the style of a true tussock moth. A couple of parallel broken crimson lines on the top and rows of white tufts on either side of the slender body with a dark shiny head, made these larvae very distinctive. The large primary nest firmly and securely fixed with strong silk fibres, which incidentally would have had to withstand the blustery wintry hostile weather of Orford Ness while its baby occupiers lay dormant, was itself a thing of amazing beauty. But as was to be expected, there were small bead-like dark scatological remains scattered throughout the nest.

A Satellite Nest

We spent a most engaging 15 minutes observing before deciding to look in again on the way home. Hoards of St Mark’s flies and, beyond the Bailey bridge over Stony Ditch, carpets of sea campion were to delight us but those are other stories! On our return three hours later (the warm sun had been out all morning) the nests were almost empty of caterpillars. Instead they were everywhere on this coastal bush, it was as if an inner voice had told each one of them: ‘go forth, fatten-up and flourish’. We saw several zealously chomping away at the young leaves. They had dispersed via the branches in all directions and to derive most benefit, it appeared as if they had managed to avoid each other. Further up the bush, we had also noticed a couple of smaller constructions, which we thought could only be satellite nests. This meant the caterpillars did not have to return after the day’s feeding to the ancestral nest further down which was probably getting overcrowded anyway. It was important that they had a refuge to retreat to for the night for protection, group adhesion and warmth. But don’t be fooled by the beauty of these beings. A gentle word of warning: do not handle or get too close because the poisonous hairs can cause rashes, headaches and even breathing difficulties!

While the caterpillars munched their way along the stems and twigs, in the process stripping the poor hawthorn, we had our own lunch to think about and so we hurrNovember 19, 2011 9:14stle.

The Main Nest, side away from the sun

      Rasik Bhadresa

Biological footnote: The Brown-tail, Euproctis chrysorrhoea (L.), belongs to the family of tussock moths Lymantriidae. A resident moth, it is found mainly on or near the coast, primarily from Hampshire to Suffolk. The adults are almost pure white with the tail end of the abdomen chocolate brown, hence the name Brown-tail. The eggs laid on the lower branches of the host plant in the summer, hatch out in late August and while still quite small the caterpillars go into hibernation in a robust silken web. In spring when active again, brown-tail larvae construct new nests until they are fully grown around June when they pupate singly or communally predominantly on the food-plant. Apart from hawthorn, the other most common plants are sloe, bramble and sea buckthorn.