Cheap Moth Trap build

In honesty, i didn’t really have much of an interest in moth until this year. My first moth night was at the start of June at Cullaloe Nature Reserve, and it really opened my eyes to moths and moth trapping.

Since then, I’ve been really keen to get into the hobby and start trapping and identifying moths for myself in my own garden.  I’m about as poor as they come, though, so I knew i couldn’t afford to buy a proper moth trap. The prices are pretty extortionate!

Since i have a little electrical knowledge (I studied Electrical Engineering at college) I figured I’d have a go at making my own. Below is what I did and how I did it.

**** WARNING – Electricity is dangerous. Do not attempt any wiring if you do not know what you are doing! ****

Now that the warning bit is over, I’ll advise that I got a DIY kit from Paul Batty. Just to quickly advise… he can provide the electrics pre-built, for those who are unsure of what they are doing, so don’t let the DIY kit put you off!

The Kit was for the electrics to power a 22w Circular Actinic tube. It came complete with tube, ballast, housing and all the required connectors. Please note, it did not come with any mains lead to plug it in (Luckily, i had a small mountain of the stuff in the garage)

Now, the only things i needed, which were not supplied in the kit was simply the mains cable and plug (as noted above) and a box to trap the moths in.

What i got was the following:

1 x Ikea box at £3.99

1 x Lid for Box at £2

1 x plastic funnel from ASDA at £0.46

I also had a few bits lying around the house, which cost me nothing. If you plan on replicating my build, you’ll also need 10m approx of 2-core cable (3-core might be preferable), a plug, a piece of plywood large enough to mount the ballast onto and an RCD adapter.

Right, now onto the build itself.

First of all, get the funnel.

then, enlarge the hole to make it easier for moths to enter.

How you do this is up to you. I started attempting it with a sharp stanley knife, but i found the plastic was a bit brittle. So, ever the inventive, i resorted to using a soldering iron to melt it! (Also has the advantage of no sharp edges). If you do try to melt it, please make sure you do so in a well ventialted area… toxic fumes and all that.

The next step is to mark a hole in the lid of the box. You’ll note from the pictures above, that the funnel has a small lip to it. You want to make the hole big enough to fit the funnel, but not the lip. (this needs relatively good measuring skills)

I’ve no photos to show of the steps from here on in. Basically, I made an attempt using a smaller box, and although it worked (in the sense that i was catching moths with it), it wasn’t big enough for purpose and i made a few mistakes on the way.

Now that you’ve marked out the hole, cut it out. Simple, really.

Now to mount the tube. The tube comes with 3 metal mounts. Simply mark the positions where you would like the mounts to go (around the funnel) and screw these into place. It’s now ready for the tube. (Don’t mount it yet!)

The next step is to mount the ballast housing. First of all, wire up all the electrics inside the ballast (I won’t advise on how to do this for the reasons mentioned above), then position it on the underside of the lid.

Grab the piece of plywood, which you’d originally cut to be slightly larger than the housing itself and put it on the top side of the lid. Screw 4 holes from the housing, through the plastic and through the wood. Basically, the wood is there to add extra strength to help support the weight of the ballast.

Fit the tube into place and connect it up.

Now, the mains cable is inside the box when you put the lid on, which is no good. The next step is to simply cut a slot in the box itself which the cable can go into.

At this point, job done! It really is as simple as that! Now just add egg cartons and it’s good to go.

The finished article should look a little something like this:

Now all you need to do is switch it on, and away you go!

The one above is the working 2nd attempt. I only built it this evening, so I can’t give info on catch rates as yet.

However, I can give info on the previous attempt. Bear in mind, the box was half the size, at best and the ballast wasn’t mounted, it was simply left lying in the box, which meant little space for egg boxes.

Also bear in mind, it’s October, so catch rates aren’t high and it’s been rather chilly here in Scotland over the past week (which is the period in which I’ve had it out)

I’ve had normally 1 or 2 moths a night. In total, I’ve had 5 species. This isn’t a lot, I’m the first to admit. However, if you take into account the following:

On my first night i caught a Blair’s Shoulder-Knot and a Spruce Carpet. As a result of the Blair’s Shoulder-Knot (3rd record for Fife), I contacted the local moth recorder. He had his MV trap out the same night and caught nothing at all. Now, there could be a whole lot of factors affecting that, but it does make me optimistic that the trap design works.

So, how much did the trap cost me?

In total, it cost me… approximately £41.50! (The electrics were £35, including P&P – plus items noted above)

Now, admittedly, i had a fair bit of the gear myself… but how much would it cost for a length of cable, a plug and a bit of plywood? I suspect, even if you had to buy everything from scracth, you’d have an effective moth trap for under £50. Not bad, I say!

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