Cooperation is better than conflict

mothsDuring May we were having a clear up in the garden and our daughter went to pick up a piece of white plastic that had got caught in a small hawthorn bush on the edge of the lawn. To her surprise it was covered in caterpillars and was not plastic; rather it was the silk tent of the Small Eggar moth’s larvae [caterpillars]. Research revealed one of nature’s less known miracles.

The Small Eggar is a social insect, rather like ants, bees and termites, and its larvae live as a colony in the very sophisticated silk tent they construct soon after hatching from eggs. With air pocket insulation and differing ‘rooms’ inside the tent the caterpillars are able to achieve better thermo regulation by massing together. They can increase their temperature by as much as 3°C in this way. When cold, they can occupy the warmer areas in sunlight and when too hot can move to the shaded ‘rooms’ where it is cooler. The colonies are typically around two hundred strong and hatch in April / May and pupate in early July. In our case, perhaps reflecting the hot spring this year, the caterpillars disappeared in early June to pupate in the grass and undergrowth around the bush. The adult moths will emerge in March or early April next year, though they can remain in pupal form for several years if conditions are not suitable.

The caterpillars all emerge from the tent and eat together, and foraging occurs at regular intervals during both daylight and darkness. Outside the protection of the tent their presence en masse allows the caterpillars to minimise their individual risk of predation. The central foraging strategy by which they leave and return to the same base allows them to communicate with each other about the location of the best and closest food sources. Caterpillars secrete a silk trail when moving outside the tent, and they can differentiate between new and older trails, and those that are unsuccessful in finding food return to the tent and pick up fresh trails left by successful feeders that are full and have returned. The build up of trails creates silk motorways over the bush stems, allowing the caterpillars to move more quickly to their feeding stations, reducing the time of exposure to predation.

Our parliament might learn from this tiny creature the benefits of co-operation for the common good!

Bystander

October-November 2019