Migrant Moths

Autumn – One of the best times of the year for catching Migrant Moths
By Tony Davison

Trapping rare moths seems to be a topical and exciting subject at this time. As Birders are keen to see rare vagrant and rare migrant birds during the autumn months, so too are Moth-ers keen to trap vagrant immigrant moths. The parallels in the two subjects are incredible and it never ceases to amaze me how such delicate insects can travel hundreds of miles and drop into a moth trap, usually in excellent condition, simply Mind Blowing. Similar to the way that the small Yellow-browed Warbler, Pallas’s Warbler and Goldcrest (The “Sprites”) arrive on our shores after a strong Easterly blow. These birds travel vast distances and again, Mind Blowing..

Convolvulus 021614Convolvulous Hawkmoth – A very large and common migrant moth from southern Europe – It may now be breeding in southern England and often does on the Isles of Scilly.

Over the years a wide variety of rare moths have been recorded in Britain. Usually the months of September and October are the best. Most arrive from Southern Europe and the Tropics and their arrival usually coincides with warm southerly high pressure systems, coming up from North Africa, the Azores, Canary Islands and Madeira. Murky weather with fine drizzle and south, southeasterly winds can be superb.

Antigastra catalaunalis 06 116Antigastra catalaunalis – A vagrant/accidental migrant from the Tropics and Southern Europe

Palpita vitrealis 06 161Palpita vitrealis (Olive Tree Pearl) – A scarce migrant from Southern Europe

There is no greater thrill than finding a rare migrant moth in the trap. It can sometimes be a MEGA, or even a first for Britain no less.

Hodebertia testalis 06 149 copyHodebertia testalis – This specimen was a first for Britain. Trapped on St. Mary’s, Isles of Scilly on 18th October 2006. This individual arrived at a time of high migrant moth activity. I was fortunate to see and photograph the specimen on 19th October, before it was sent off to the Natural History Museum, for confirmation of it’s identity. In “mothing” terms, a MEGA, an awesome moment and it doesn’t get much better than this.

One of the best places in Britain for trapping rare migrant moths is on the Isles of Scilly and over the years I have been fortunate to have caught a number of good immigrant moths whilst on holiday on the small island of St. Agnes.

Merveille du Jour 027613Merveille du Jour – This specimen was certainly the “Wonder of the Day”. I found it in my trap on 15th October 2006, whilst moth trapping during my holiday week on St.Agnes, it was a first record for the Isles of Scilly.

Vestal 06 164Vestal – Pink individuals indicate long distance migration from warm climates.

Hymenia recurvalis 06 236  Hymenia recurvalis – A rare autumn migrant from the tropics. This specimen was the 2nd record for St. Agnes, Isles of Scilly – October 2006.

Old World Webworm 06 226Helula undalis (Old World Webworm) A rare migrant from the tropics

Delicate 037615Delicate – A common migrant often arriving in large numbers – It may breed in Southern and SW Britain.

Gem 081616Gem – A scarce migrant from Southern Europe and North Africa. The Gem can be an indicator of good migrant activity.

The arrival of migrant moths are not limited to our of islands and coastal areas. Many get trapped by moth enthusiasts from a number of inland counties. For example, from my small South Derbyshire garden, I have caught a variety of good migrant moths over the years. A second record of Ni Moth for Derbyshire, several Rusty Dot Pearl, Small Mottled Willow, Vestal and Scarce Bordered Straw, all vagrants to my county.

ni-moth3Ni Moth – This specimen was a complete surprise, I nearly passed it off as a Silver Y. A second record for Derbyshire.

Scarce Bordered Straw 16th Sept06 025 Scarce Bordered Straw – During the autumn of 2006, an unprecedented arrival of this species occurred in Britain. During this invasion, the species was added to the Derbyshire list

Small Mottled Willow 06 112Small Mottled Willow – A common migrant but a scarce immigrant to Derbyshire

Rusty Dot Pearl 9158593Udea ferrugalis (Rusty Dot Pearl) trapped in my garden as recent as 16th October 2014

Dark Sword-grass 06 055Dark Sword Grass – A common migrant that can turn up anywhere, during any month.

Crimson Speckled 06 268Crimson Speckled – One of the most sort after rare moths.

In recent years, moth trapping has become an increasingly popular hobby, especially amongst Birders. There are possibly more people “Moth Trapping” now than in the last 20 years. The status of Britain’s moths has recently been published in a superb book by Butterfly Conservation. Millions of records of moths are now held by the National Moth Recording Scheme (NMRS), and a comprehensive picture is now beginning to emerge. This can only be achieved by the many Moth Recorders submitting their records. As more people become involved in moth trapping and recording, the knowledge of our moth population and our ability to conserve and protect it, will undoubtedly improve.

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