Moth traps …… what are the options?

During this pandemic I’ve been running my moth traps in my garden to keep myself occupied and have been posting pictures of what I have caught on a daily basis on my Twitter feed and my Facebook wall. As a result I have had a number of people contact me to ask about where they can get a moth trap from. I thought it might be helpful if I wrote a piece about some of the considerations to take into account when buying or making a moth trap. These are simply my views which I have come to after moth trapping on an off for about 30 years, others may see it differently and may wish to comment accordingly.

Moth traps come in different shapes and sizes, use different types of bulb and can be powered in various ways. To the beginner this can appear confusing. I will set out my views here, to help you through the labyrinth.

Power supply
At their simplest moth traps consist of a container to catch the moths in and a bulb to attract them. (Just to be clear, the moth traps I describe here do not kill the moths, once caught you identify them and then let them go). In order to light the bulb you require a power supply, the options are the mains, a battery or a generator. Moth traps designed to use the latter two are more (and much more) expensive as you require a battery or a generator and have been designed for use in the open countryside where you will not have access to mains power. So …. If you intend to run a moth trap in your garden then a main powered moth trap utilising an extension cable is, in my view, the obvious choice for the beginner. If, in due course, you want to moth trap in remote locations you might then consider getting a battery powered trap or a generator.

For decades the default bulb used by moth trappers was a 125w (or 160w) Mercury Vapour (MV) bulb which run off 220v mains. These default bulbs also require what is known as a choke (or ballast) which in simple terms is a little box of electrical components which stop the bulb from immediately blowing when you switch it on. However in recent years the manufacture of MV bulbs has ceased due to concerns of mercury pollution should the bulb shatter. And here is the dilemma … MV bulbs catch, in my experience, a greater number and diversity of moths than the ‘replacement’ options I will discuss later. It is still possible to acquire MV bulbs from certain retailers but at some point in the future, supplies will run out. As a result moth trappers who use MV bulbs tend to carry a stock of bulbs for use in to the future. Each bulb costs around £20 and some suppliers limit the number of bulbs you can buy to eek out the stock. When buying spare MV bulbs it is also important to buy the right fitting – some are screw in, some 2-pin and some 3-pin bayonet types.

MV bulbs are also very bright (never stare at them or they will damage your sight). So if you live in a urban area an MV light may annoy your neighbours and attract complaints.

I also have a couple of Philips 160w ML ‘blended bulbs’ which can be runoff the mains without the need of a choke. From the internet, it would appear that such bulbs are still available and are an option worth considering if you wish to make your own trap and sort out wiring up the bulb. Again these bulbs are very bright.

MV bulbs and blended bulbs run very hot and as a result they will shatter if it starts to rain, so they are protected by rain guards or a commercial empty Branston pickle jar (see later in the traps section). However, if treated with care these bulbs will last many years of use.

Another variant to consider especially in urban areas is the use of a ‘black bulb’ (see here) – these again run off the mains but are only 25w and because their design produce considerable less light which is visible to humans but they do allow ultraviolet and infra-red light to be emitted so are good at attracting moths. Again, such bulbs can be purchased and a trap and electrics assembled around it.

The next type of bulb to consider is an actinic bulb, these bulbs do not have the mercury issues. They were originally used in moth trapping at remote sites where they were powered of 12v batteries. However now by using a ‘plug-in converter’ they can also be run off the mains. Some of these bulbs are 20w and some 30w, some suppliers sell traps with two 20w or 30w bulbs.

Finally, ‘bulbs’ have been developed for moth trapping which are LED lights. These run off batteries, they are compact systems which are a good travel option in remote areas but their performance when compared to an MV light is considerably reduced.

In essence there are three main types of moth trap used by amateur naturalists, all named after the lepidopterists who invented them.

In no particular order, firstly there is the Skinner Trap which is basically a rectangular box with angled perspex lids which allow the moths to enter into the trap (which is filled with some egg trays where trapped moths can rest out of the light). My first trap was an aluminium Skinner trap but most today appear to be plastic or wood.

This is a flat packed aluminium Skinner Trap with a choke (rectangular box), an extension cable and the MV bulb stored inside a pickle jar – jar put over the bulb when lit to stop rain hitting and shattering it.

Skinner trap assembled – with the two persplex lids

Second is the Robinson Trap – a circular trap which works in a similar way. This is bulky trap which unlike the Skinner trap cannot be flat packed. It is my trap of choice in my garden.

MV Robinson Trap with choke

Finally is the Heath Trap which also flat packs and we designed to be easily transported to remote locations.

Portable Heath Trap (can be flat-packed) with its Lithium Tracer 22aH battery

There are variants on these three types, for example there are those who have designed their own traps either using wood or circular or square plastic storage containers. Google ‘moth traps’ or look at this booklet.

Battery operated moth traps were designed to use in remote locations and on holiday. In the early days I used car or motorbike batteries, which take quite a bit of lugging about. These have been replaced by lithium batteries which come in various sizes depending on the output of the bulb type and bulb set-up in use. The batteries also need to be charged from the mains after each outing. These batteries are also expansive, costing more than a trap set-up in many cases. My batteries are Tracer batteries, an 8aH to power my twin LED Skinner Trap and a 22aH to power my actinic Heath Trap.

Portable compact LED Skinner Trap with is Lithium Tracer 8aH battery

So, what to do?
As you can see there are various options! If you want to run a trap in your garden then I suggest you get a mains powered trap running an actinic light source and the moth cost effect trap with a Skinner type trap.

There are many suppliers of moth traps, I have bought all my recent traps from Anglian Lepidopterist Supplies – here is the link to their range of mains driven traps, either the compact Skinner or the double compact Skinner would be my recommendation.

There are other suppliers I have used such as Watkins and Doncaster – see here or the NHBS – see here.

If these traps are outside your budget or you are not sure whether you will use the trap very much perhaps got for a black bulb (here) and make your own.

Sugaring and wine roping
Not all moths are attracted to light (and indeed there are many species of day-flying moth). Sugaring and wine roping are ways to attracting the night flying moths which do not come to light. This link gives you a couple of recipes which you can try out. Moths fly most when the night time temperature in above 14 degrees and it is not a full moon.

Final considerations
In the UK there are over 2500 species of moth of which approaching 900 are ‘macro-moths’. This is the best field guide for identifying them.

Then there are 1600 species of ‘micro-moths’ – smaller and trickier to ID, however some micro-moths are bigger than some of the macro-moths ….. Many are featured in this guide.

This book contains photos of all 2500 species.

The only other thing you will be (aside from patience) are some pots to put you catch in, in advance of identifying them. The three suppliers listed above sell such items.

I hope this has been helpful ….. have fun.








The Wonder of the Day

This autumn moth the Merveille du Jour is one of my favourites. Its name derives from the French meaning Wonder of the Day.

The adult moth flies in September and October and often feeds on ivy flowers and fallen fruit.

Its distinct colours and patterning enable it to lie hidden during the day on lichen covered trees.

The caterpillars feed in the spring on newly emerged oak tree flowers.

Four-spotted Footman – female and male

This is a Nationally Scarce A species of moth which means it lives in less than 100 ten kilometre squares in the UK. I have trapped the male of the species several times before but have never seen a female – I have two in the trap the other night.

The female has four spots on her wings (one is hidden under a wing)

Here is a close up

Here is the male for comparison – no spots!

A Four-spotted Footman and Black Arches

A couple of striking moths in the trap this morning

This is a Four-spotted Footman – it is a male, the females have the spots. It is a rare moth, designated as a Nationally Notable A, it is reasonably well distributed in the south west and I record it in my garden most years. Its larvae feed on lichens.

This pretty moth is Black Arches – a local species residing in the south of the UK. Its caterpillars feed on oaks.

Burnished Brass

Following on from yesterday’s blog about the Beautiful Golden Y, today the trap contained a closely related species – the Burnished Brass, so called because of its shiny ‘metallic’ scales.

It is a common species throughout the UK and its caterpillars feed predominantly on nettles.

Burnish means to polish metal