The Hebrew Character Moth, and a few notes about moth migration

Appearance

The Hebrew Character, Orthosia gothica, is a member of the Noctuidae family and named after the prominent mark on each of its wings which resembles the character ‘nun’ in the Hebrew alphabet or the form of a gothic arch (hence the scientific name gothica).

It is a medium sized moth about 3.5cm long with wings about 1.5cm in length and varies in colour from grey to a reddish-brown, with moths in the North of the British isles having a mark which is paler and nearer to the background colour compared to those in the south.

Habitat and lifecycle

It can be found in a variety of habitats, from bogs on upland moors to urban back-gardens, and is most frequently seen from early April through to June. In winter it hibernates as a pupa in an underground cocoon, with the fully-formed adult staying inside ready to emerge in spring.

The caterpillars can be found from April to July and feed on the leaves and buds of a variety of plants including the Birch and Oak, mainly feeding at night and hiding during the day. The adult moths feed on the nectar of Sallow and emerge quite early in the year, they are also more active at night, being very easy to attract to moth traps.

Migration

In an earlier article I wrote about moth trapping I covered a few of the methods of going about attracting moths like the Hebrew Character, such as baiting, and now we are in spring more species of moth have emerged from hibernation or are migrating to the British isles, here are a few notes about how an insect so small is able to migrate long distances;

Flying High

Flying insects such as moths will take advantage of rising thermals and strong winds to climb to altitudes of several hundred metres to a few kilometres in order to take advantage of the high wind speeds at those heights which will propel them to places they seasonally migrate to.

These speeds are many times greater than that at which an insect could fly unaided and scientists have estimated that by harnessing these winds insects may be able to travel up to 2000km during only three or four 8-hour long flights.

Directional Sense

Lepidopterists (this is the name for those that study moths) have also discovered that they possess a clear directional sense and will fly at an angle to the prevailing wind so as to control where they end up. They do this by using a specialised organ called the ‘Johnston’s Organ’ at the base of their antennae, this organ helps them maintain their sense of balance and orientation during flight.

One theory about their manner of navigating is that they use the light of the moon as a beacon but exactly how they do this is a mystery, one thing that is certain is that a clear night sky with a full moon is the best for moth catching, and the most pleasant night to be out and about for moth and man alike.

A B-H