Moth Trap: my "Really Userful" guide

 Making a moth trap is a pretty easy project

 

I think I've illustrated this in a few old posts.

But recently someone asked about making the one I use, so here is a slightly better write up.

I'm not going to give dimensions for parts, especially for wooden parts where you can use whatever you may have laying around. Hopefully, I'm providing just enough info for a successful build without too much need to improvise. But naturally, if you what to experiment and changes things, go ahead!

Poplar Hawk Moth (Aldwick, early May 2025)

This design uses a readily available “Really Useful Box, Plastic Storage, 35 Litre” (about £20 from Amazon).

Other required parts:-

    • 20W ES Energy Saving Ecolite - UV Lamp (a 13W version is also available)   https://www.tlc-direct.co.uk/Products/LACFL20UV.html
    • ES bulb holder
    • 3 core, 3A or 5A mains cable (& suitable cable clips)
    • 13A plug fitted with a 3A fuse
    • wood; for lamp support frame & card blocks
    • card; photo mount card is ideal
    • picture hooks
    • egg boxes

Card Blocks

These are just 2 small pieces of wood to prop up the card sides and keep them about 25mm apart.
So you could use whatever wood you have, within reason.
Mine are each 80 x 40 x 15mm thick, with the corners cut out to provide a suitable 25mm central section. These are drilled & screwed to either end of the box, so the tops of the blocks are about 100mm from the base.

What you are trying to do is create a suitable angle when the card sides are fitted; too sharp an angle and there won’t be enough space behind the cards for egg boxes. Too shallow, and (maybe) the moths wont drop readily into the trap.

Lamp Batten

Once again, you could copy my lamp support, or make something using material that you already have.

The idea is to end up with a lamp support system which sits below the level of the box lid; this is useful for storing the box with the lid on and also, at the end of the night, its handy to pop the lid back on to keep the moths in place until you are ready to examine them.
Its also useful to allow the bulb to tilt upwards; i.e. bulb level for storage, tilted upwards slightly to ‘throw more light outwards’. I’ve done this by just using one screw either side of the wooden piece holding the lamp base.

Wiring

At your own risk!

Please replace 13A plug fuse with a 3A fuse.

If the lamp holder is plastic, you can use a 2 core, 3A or 5A mains cable. But if metal (brass) it should be earthed, so use a 3 core, 3A or 5A  mains cable.

Clip the cable to the side of the wooden lamp batten to stop the cable twisting when being handled, and to relieve any strain on the wire connections within the bulb socket.

Cut a small slot in the side of the box, so the cable can sit in it when you close the lid.

Card sides

Most Skinner moth traps have glass or clear acrylic sloping sides, but this is not for the benefit of the moths. In my tests, I couldn’t see any difference in moth numbers either way.

You could cut acrylic sides, but you will find you need right-angle corners on one edge, curved corners on the other and a certain amount of trimming to get them to fit snugly ...tricky!

Obviously using card, you should avoid putting the box out at night if there is a risk of rain. But if the card (& the egg boxes) get destroyed, they are easily replaced.

I’ve used black mount card; white side up, black side down to (maybe) keep it darker inside the trap. I’ve also used a picture hook to hold the card closer to the inside of the box.

Egg boxes

Stash a few egg boxes under the card sides to give your moths somewhere dark-ish to settle down over night.

Ready to deploy!

Tilt lamp slightly upwards (...if possible, but not essential) and place cable in box slot.

Place trap in a suitable location (‘suitable’ = safe & easy to connect to mains).

Do not look directly at the bulb when its on, unless you are a few metres away!
The bulb is considered safe, but why look at a bulb that radiates UV light?

For best results (& to avoid too many escapees) get up as soon as it gets light, switch the power off, fit the lid & then go back to bed!

Happy Trapping!

male Muslin moth

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