Beautiful caterpillars
Friday 12th August 2022 was Assynt Highland Games day in Lochinver. The games are held annually in the Culag Park just a short walk from the breakwater at Lochinver’s harbour.
What we didn’t know then was that the breakwater was also hosting a brightly coloured event all of its own. Numerous caterpillars of the Vapourer moth, Orgyia antiqua were on the move all along the metal railing of the breakwater.
This second event came to our notice over that weekend. We paid a visit a few days later and counted at least a dozen of these beautiful caterpillars. Some were on the railing and some were happily munching on the leaves of the stunted trees that had taken hold in the breakwater’s boulders.
A closer look also revealed masses of cocoons attached under the top rail. In several places, female moths were present next to their recently laid eggs.
High flyers
The male Vapourer moths fly mostly high and during the day and are not often seen. The females however only have rudimentary wings and aren’t capable of flight.
Once a female has emerged from her cocoon she emits pheromones to attract a male. These ‘vapours’ are detected and tracked by the males using their comb-like antennae.
After successful mating the female will lay 200-300 eggs on the remains of her cocoon. She will die shortly afterwards.
The males die during the late autumn, but the eggs, which have a very hard shell, will overwinter.
The following spring the eggs hatch and the process begins again.
Protection
Once fully grown the caterpillars spin a thin, transparent, silky cocoon. The cocoon doesn’t seem to offer much protection, but the caterpillars weave those long body hairs and ‘antennae’ into the silk! Why?
These hairs are defensive in life and at the cocoon stage so, incorporating them into the weave is a deliberate act to offer some protection.
The hairs can be mildly irritating to humans and could cause skin rashes or allergic reactions to more sensitive skins.
The compilation of photographs here show hatched eggs, a female near her eggs, a closer look at the eggs and finally mature caterpillars.
Simply amazing.
A subsequent visit on 9th September revealed that more cocoons were present but that most of the large beautiful caterpillars had ‘disappeared’. Caterpillars that were still present were much smaller.
One huge piece of luck was the presence of a single male moth which was hastily photographed on a phone. You can clearly see the huge antennae used by the male to detect the pheromones emitted by females.
DnA Haines