Heart and dart moth in trap

Build your own Moth Trap

Moths are a widespread and diverse group of insects, but they can often be overlooked. A large part of this is due to many species being active at night, meaning that people have fewer opportunities to interact with them. They also rely heavily on camouflage and have a reputation for being more ‘drab’ in colour than their day-flying butterfly relatives.

However, there are many exceptions to these general rules. Beautiful species of brightly coloured day-flying moths exist in the UK and abroad:

Cinnabar moth. Richard Preece
UK Cinnabar moth. Credit Richard Preece
Madagascan Sunset Moth. University Museum of Zoology collection. Copyright University of Cambridge
Madagascan Sunset Moth. University Museum of Zoology collection. Copyright University of Cambridge

It is also unfair to say that nocturnal species (active at night) are ‘drab’. Although some are less flashy, they are equally beautiful in their own right, with intricate patterns that help them blend in with their surroundings.

Heart and dart moth, UK
Heart and dart moth, UK

We may not see many moths in our day to day lives but that doesn’t make their impact any less significant. There are upwards of 2.5 thousand species of moth in the UK, compared to roughly 60 species of UK butterfly.

Recent research suggests that this diverse community of moths act as important night-time pollinators, possibly rivalling or even surpassing the daytime pollination efforts of bees!

Day-flying hummingbird hawk moths can be seen drinking necter in August

Sadly, both butterflies and moths are declining. A report on the state of Britain’s moths in 2013 showed that two-thirds of the common and widespread larger species had declined over the last 40 years. This doesn’t count the many species of micro moth we also have in the UK.

It is therefore important for people to get to know their friendly neighbourhood moths in more detail. This will enable us all to help support this diverse and important pollinating group that is currently on the decline.

Discover the moths in your ‘back-yard’

There are a large number of free resources available online with information on moth identification, their status in the UK and how to support them.

There are lots of free guides that take you through the steps of making a moth trap:

The Wildlife Trust has two excellent moth-watching guides here:

Butterfly Conservation also have some great guides for building your own light traps, which are harmless bits of equipment that attract moths towards a light source and into a bucket, where they can then be observed before release:

Butterfly Conservation: budget bucket moth trap

We followed their advice and made two moth traps of our own:

Bucket trap: One is a cheap bucket trap, which is basically a bucket with a funnel and light on top of it. This is great if you want to get into moth trapping but does require the purchase of some specific parts. See the link from butterfly conservation above for step by step instructions and a full parts list.

Sheet trap: The second moth trap is much simpler and can be made using items found in most households. All you need is a white sheet and a torch:

Step 1:

White sheet hanging on washing line

Hang a white sheet up on a washing line using some pegs and turn off any bright lights that are nearby.

Step 2:

Then shine a torch on the sheet, sit back and wait for the moths to fly in.

Step 3:

Take a picture of the species you see so that you can use the identification resources below later.

Do not try to ‘catch’ the moths as our hands can damage the scales on their wings.

Why do night-flying moths like bright lights so much?

One suggestion for why moths are attracted to bright lights is that our artificial lights disrupt their navigation system. The moon is usually the brightest natural source of light in the sky. Moths orientate themselves relative to it as they fly, similar to how sailors navigated using the stars.

However, artificial lights now produce competing light sources. A passing moth may try to navigate using street lamps or house lights instead.

As the artificial light will be a lot closer to the moth than the moon, when the moth moves the position of the light source changes. This causes them to spiral in towards the light, as the saying goes, ‘like a moth to a flame’.

Identify: what did you see?

Identification guides help you to identify what you have found. Take a picture of your moth and visit the sites below later to match them up:

UK moths. University Museum of Zoology collection. Copyright University of Cambridge
UK moths. University Museum of Zoology collection. Copyright University of Cambridge

The Wildlife Trust has the below young-person friendly guide for commonly found UK moths:

We found these with our bucket moth trap:

Caterpillars and pupae

As with butterflies, the young life stage of a moth is called a caterpillar, which pupates and undergoes metamorphosis, where it transforms into an adult.

Many caterpillars search out a safe place to pupate and hunker down amongst piles of leaf litter and soil. Therefore, be careful when tidying up your garden so that you don’t damage them.

If you do find any caterpillars or pupae, you could also place them in a sealed container so that you can see what emerges as an adult.

This is what we did when we found some caterpillars in our garden this spring. They have just started to emerge from their pupae so you may well see some new moths in your garden soon!

The caterpillars will need a supply of food but are usually easy to keep and advice can be found from the Amateur Entomologists’ Society

photograph of a large yellow underwing moth caterpillar on a leaf
Broad-bordered yellow Underwing

Find out more…

Wildlife Trust: How to attract moths to your garden

Gardening for butterflies will benefit night-time moth visitors too

Insect curator Ed tells us why ‘weeds’ can help our local wildlife here: wildflowers not weeds

The Esmée Fairbairn Collections Fund is run by the Museums Association, funding projects that develop collections to achieve social impact.

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