Moths on the move

Mike Thornton, SNH Operations Officer for the Forth Area, describes how integral moths are to Scotland’s biodiversity, and why it’s crucial to know how their populations are changing.

Taynish NNR_ Moth Trapping 2019_m180036 - swallowtail moth

Swallowtail moth. (c) Caroline Anderson/SNH.

I lift the egg cartons out of the moth trap, slowly revealing a range of beautiful species – Burnished Brass, Mottled Beauty and Elephant Hawkmoth, all having been attracted to the light on the trap.

Like many insects, moths form an important part of our biodiversity, with about 2,500 species recorded in Britain and Ireland, and 1300 in Scotland. As well as being beautiful insects, their population trends reveal much about the general health of our environment. They pollinate plants and play a central role in food chains, providing vital food for bats and birds.

Throughout the ages, they have inspired the human spirit, and driven curiosity about nature, with Victorian collectors giving them some exotic names such as Deaths Head Hawkmoth, Garden Tiger and Lunar-spotted Pinion.  Although moths are mainly nocturnal, they are very similar to butterflies, belonging to the insect order, Lepidoptera (derived from Greek, meaning scaly wings). However, there are many more moths than butterflies, and they make up around 90% of all Lepidoptera species.

Taynish NNR_ Moth Trapping 2019_m180115 - large emerald moth

Large emerald moth. (c) Caroline Anderson/SNH.

The distribution of these fascinating insects has now been mapped across Britain and Ireland for the first time in the groundbreaking Atlas of Britain & Ireland’s Larger Moths, the results of the National Moth Recording Scheme, a citizen-science project led by Butterfly Conservation and Moths Ireland and supported by SNH.  This publication provides important baseline information on the distribution, abundance and conservation status of almost 900 species.

The project has revealed mixed fortunes for our moths, with some species showing long-term increases in distribution and abundance, and others showing worrying decreases. Some changes are most likely caused by climate change, which is driving the northwards expansion of some species, while other moths are suffering from the impacts of intensive land management.

Taynish NNR_ Moth Trapping 2019_m180102 - cinnabar moth

Cinnabar moth. (c) Caroline Anderson/SNH.

For example, since the Buff Footman Moth reached Scotland in 2008, we have seen a huge increase in numbers and distribution, possibly in response to cleaner air and climate change. Conversely, for more northern species, such as the Grey Mountain Moth, climate change may be causing them to retreat to upland areas.  Many moths have also changed their life cycles in response to warmer spring temperatures, with some species flying almost three weeks earlier than they did in the 1970s.

Since 2012, I have trapped over 130 moth species in my small North Berwick garden, and given the major changes we are seeing in their distribution and abundance, I may well see some new species colonising and others disappearing in the future.  If you want to get involved in moth recording, you can find out more at


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