The Moths of Havergate

Whilst I have an interest in most of our smaller creatures the principal draw is towards moths. On my mothing trips to the Island I have run 3 light traps on a portable generator. Moths drawn into the traps rest on the egg trays provided inside and are sorted through after dawn. The aim is to identify all species. The records are sent to the RSPB and the county moth recorder for inclusion in the national recording scheme. It is important to choose the most suitable weather conditions for insects flying as the wind that is a common feature on the exposed coast greatly reduces flying. Cloudy, warm, humid and calm conditions are perfect but different species fly across the seasons so the full year must be considered.

Moths are insects and pass through all the stages of metamorphosis, egg, larva (caterpillar), pupa and adult. Whilst many adult moths feed on nectar/water it is the larval stage that does the growing. Most (not all) feed on plants and some are very fussy about which plant or even which part of the plant they feed on. Havergate Island is estuarine and so possesses salt-marsh with its specialised plants and it follows, specialised moths to go with them. The coast also has a more even temperature compared to inland, especially milder winters. There is salt spray so coastal plants that can survive that, have a competitive advantage and also bring the moth species to match. There are also moth species that will have a competitive advantage where the winters are milder too.

There is gorse on Havergate, so three common species that feed on it have been found: Coleophora albicosta, Epinotia ulicetana and Pempelia genistella (photo). Endothenia oblongana (photo) occurs. Its larvae feed on the roots of plantain that is found on the shingle near the huts. All of these are ‘micro-moths’. This is a bad term as many micro-moths are larger than some of our macro- or larger moths, but the term is based on the average size of a moth within a particular family and nothing more.

Two larger moths that are abundant on the island are the Tawny Shears with a larva feeding on the Sea Campion (especially the seed pods and flowers) and the Dog’s Tooth (named after the sharp black mark in the centre of the forewing). Both these species can be found inland too but less commonly.

The Cream-spot Tiger is another UK wide species that is especially common on the Island as is the Yellow Belle. Neither of these is fussy on the foodplant but the Rosy Wave is. Its larvae feed on Sea Beet. The rosy tint is often clearer that in the photo. The Lime-speck Pug is another UK wide species that seems to thrive on the island and particularly on salt-marsh. The larvae of this moth feed on flowers, particularly petals.

Two larger moths that are particularly attached to the coast are the Sandhill Rustic and the Saltern Ear. Both have larvae feeding on grasses but the Sandhill Rustic specifically feeds on the Common Salt-marsh Grass, Puccinellia maritima. The Saltern Ear can be found less commonly inland but the Sandhill Rustic is very much restricted to coastal salt-marsh. There are four recognised sub-species of the Sandhill Rustic each with a restricted distribution. The one we have in Suffolk is the commoner sub-species found from North Kent to Aldeburgh.

The Ground Lackey is another moth, that in Britain, has a restricted coastal distribution being found in Devon, Kent, Essex and Suffolk. The larvae feed on salt-marsh plants. Strangely it is not restricted to the coast where it is found on mainland Europe. The female is larger than the male but both are variable in colour and markings. I think the Star-wort is a very smart looking moth. It is a coastally based species with the larvae feeding on Sea Aster and Sea Wormwood flowers but wanders inland and can be found feeding on related plant species inland. Monopis monachella is a Suffolk speciality. It is established on the Suffolk coast and only rarely wanders inland. It can also sometimes be found as an immigrant elsewhere in the UK. The larvae feed on waste from birds such as feathers skin and faeces. It is in the same family as ‘The Clothes Moth’. This group of moths feeds on animal waste such as fur, feathers and skin. A related species Monopis laevigella was found in the old tractor shed before it was cleaned out, feeding on the waste from the Barn Owl and Woodpigeon nesting there.

Psyche casta is not specific to the Island or the coast. It can be found across the UK. It occurs on the island and has an extraordinary life style. It is most commonly seen as the larval case (photo) seen fixed to posts, walls, tree trunks during early summer (you will also find one in the toilet cubicle). Only the female larva crawls up posts to pupate. The adult female is wingless. The sooty winged males fly in early morning sunshine and have very developed antennae to detect the pheromones of newly emerged females. After mating the female lays her eggs inside the larval case. After a few days the young Psyche casta hatch and devour the body of their mother as their first meal. They cut up her larval case to make little ones of their own and then crawl or drop to the ground to feed on anything they can get their jaws into. The cycle continues.

A brief look at salt-marsh micro-moths. Very interesting to me but some are not easy to identify and can just be referred to as small brown jobs. Scrobipalpa is a genus of moth of which the larger proportion of species are specific to salt-marsh or coastal plants. I have found 7 species on Havergate Island so far. The one photographed is the commonest in the UK, least food fussy and probably the plainest in appearance of the salt-marsh species. Agdistis bennetii also known as the Salt-marsh Plume or ‘Y’ Plume is another common species on the salt-marsh. Its larvae feed on Sea Lavender. I have also captured an individual of Coleophora aestuariella which makes Havergate Island the most northerly location for this moth. The larvae feed on Annual Sea-blite.

Raymond A Watson