LED Moth trap (1 Viewer)

pppppvvvv · Jul 4, 2017

If anyone is interested, I have spent time making an LED moth trap, using the electronics design in the book "How to build your own moth trap", and based the box on a DIY design that I saw somewhere on birdforum.

Initial results using the above book's single purple LED weren't good at all, so I replaced the single T10 LED, with a range of LEDs from futureeden, which seem to have brought in better results.

Results seem pretty good, not quite as good as the MV trap I used to run in my garden, but not awful. Maybe 70-80% of numbers and species.

A few new species for the garden so far, but no Hawkmoths which is strange, although early days yet. (The MV trap would have regular Poplar and Elephant)

Of course it has the advantage that it is lightweight and totally portable, which I aim to exploit in the future.

I have yet to resolve the waterproofing of the LED / wiring. I initially used a clear plastic cover, but that must have stopped the UV as I got no moths with it fitted. I will use black tape over the wiring instead to give it some protection whilst leaving the LEDs uncovered.

Total cost was around £70 I guess. Uses 16x rechargeable AA batteries which is a bit of a pain, but I do get two nights per charge. Someone with better electronics knowledge could probably improve on this. (I was just happy to get here without blowing the LEDs!)

DMW · Jul 4, 2017

Thanks for posting that. Looks a good solution for a low cost portable trap. Are the LEDs bulbs in your array different colours? If so, it would be interesting to know whether some are better than others, or if it's just a matter of having enough of them to give off a decent amount of light.

pppppvvvv · Jul 4, 2017

Hi,
I have gone for an array of colours, the UV purple (380-390nm) I'm pretty sure bring the moths in. I have 4 of them!
Plus 2 full spectrum (380-840nm), and 1 blue (440nm) and 1 green (520-530nm).
These ranges seemed like a good fit according to the limited information I found on the web.

These LEDs are all hard soldered and glued in place now, so it would be difficult to experiment further with different combos. Plus no two nights are same.
8x UV purple might bring higher numbers, but some species might only be coming in for the Blue or Green.

Also, I might be missing something compared to the MV, which would explain no Hawkmoths.

I'm just relieved, after all the ordering parts off Amazon, soldering, and wiring, that I have something workable!

There is a Health and safety warning with the UV LEDs. You shouldn't look at them, and I give them a wide berth to be honest. The book mentioned above includes a dawn/dusk sensor in the design, so I can set it up and empty it when the LEDs are off.

DMW · Jul 4, 2017

Useful to know, thanks. Might have a go myself.

pppppvvvv · Jul 7, 2017

Well, I ran the MV trap last night (I've had a break for a few years now), and it was much better than the LED trap.. I would say twice as many moths in the MV.
So, the LED is more portable / (disposable!) for remote areas, but not a replacement in the garden, or near a mains supply.

pppppvvvv · Feb 16, 2021

I still use the LED trap, in fact have two now, both home made. My thinking is that although it's not as good /powerful as an MV bulb, one night in good habitat gets me more interesting species than many nights from the garden.

It is a labour of love tho. A faulty battery pack took a while to diagnose, and I damaged a few rechargeable batteries as a result. I think I'm back in business now.

I'm hoping to build a 3rd electrics kit as a spare which will hopefully get me thru the year.

Has anyone else had success with LED?

pppppvvvv · Mar 28, 2022

My LED setups still work, after all these years(!) And get a few good species from more remote locations, that I don't see at the garden traps.

I tried cheap uv365nm torches with very little success when they were pointing away from the trap.
However, aluminium funnels seem to make a difference, pointing the torches down against the sides of the funnel.
Seems to get a nice glow, and it does draw moths in, providing the surrounding area is really dark. Batteries last a night in the summer months.
Have ordered cheap Mobile phone stands to point the torches in the right direction.

Pointing downward, I don't have to worry about rain, so I've removed the lens/filters from the torchesfor a wider UV range

pppppvvvv · Apr 13, 2022

My original LED trap is out in local woodland now. Have high hopes for this mixture of broadleafed woodland, fallow grassland and abandoned meadow, with a stream running thru.

Last night's moths included Red Chestnut, which I have never recorded in my garden 1km away. The woods have a good population of Cloaked Carpet in previous years.

pppppvvvv · Jun 4, 2022

Something weird about the UV torches, they attracted very little in the garden, during the spring, to the point where I gave up on using them.
But trying them at a New Forest licensed site last night, and they were as good as the UV LEDs.
(This is good news as the light is barely visible to people, and the torches are fully waterproof.)

Perhaps the batteries only last a few hours, so they need shorter nights to stay effective thru the dead of night.

So, worth experimenting with them thru the summer, although I wouldn't have the confidence to rely on them solely just yet. Need a few more good nights to prove this wasn't a fluke, and then maybe buy an extra torch to improve the glow! 4 would be ideal as the charger can take 4 batteries.

pppppvvvv · Jun 6, 2022

Purple Bar seems to agree

pppppvvvv · Jun 20, 2022

Another electrics set made for the moth traps. This one was 8x 395nm 3w LEDs.

I need to reduce the voltage in the transformer as the 8xAA batteries aren't lasting the night, but it was giving out an impressive glow, and pulled in a decent number of moths by my back garden's standards.
( How I have never blown a set of LEDs is anyone's guess)

pppppvvvv · Aug 23, 2022

Spoke too soon and dropped this one on the way to my hidden moth trap lol. Damaging a couple of LEDs.
Easy to diagnose which are blown by turning down the voltage and tapping the terminals individually.
Still having issues with this one and setting the voltage so it lasts the night.
So I'm running it with UV torches so some light makes it until dawn, otherwise the whole trap's contents is likely to just fly off in the darkness!

pppppvvvv · Aug 28, 2022

peter.jones said:
Spoke too soon and dropped this one on the way to my hidden moth trap lol. Damaging a couple of LEDs.
Easy to diagnose which are blown by turning down the voltage and tapping the terminals individually.
Still having issues with this one and setting the voltage so it lasts the night.
So I'm running it with UV torches so some light makes it until dawn, otherwise the whole trap's contents is likely to just fly off in the darkness!

This electrics set is proving a nightmare, and what started out as a well designed moth light is now a complete dogs dinner!

The batteries won't power these 8 LEDs all night. So I've bipassed 2, and am winding down the voltage to hopefully find a balance between a bright output from 6 LEDs, and the batteries lasting 9 hours.

I'm lacking the necessary electronic knowledge to work out what exactly is going on! Which doesn't help.. I will not rest until this light set has a trap full of moths!!

chipperatl · Sep 2, 2022

Can the LED's be powered off a USB? This power jumper on my desk I needed to charge my phones during power outage just brought that to mind. It is used to jump start dead car, but has USB output and can be used as a battery. 12KmAh version. I bought a 20K version to jump start my truck. They are rechargeable also.

Atropos · Sep 2, 2022

peter.jones said:
Well, I ran the MV trap last night (I've had a break for a few years now), and it was much better than the LED trap.. I would say twice as many moths in the MV.
So, the LED is more portable / (disposable!) for remote areas, but not a replacement in the garden, or near a mains supply.

Just re-read this thread. I recently bought a LepiLED system that runs off a 30000ah powerbank. Very impressed so far whilst numbers of individuals are certainly lower the diversity if probably about 80-90%. So far have only run it in the Dry season here were numbers are far lower anyway but have had nights solely with the LepiLED with 120+species which for the time of year is excellent. I tend to run them together with an MV (take a honda generator with me) and find they compliment each other and bring different species in

pppppvvvv · Jun 12, 2023

Moving away from UV LEDs, and sacrificing some of the portability this year..

I've had some good overnight results with a portable battery and blacklight.
The battery inside my campervan so it's dry and safe.
This gives quite a few more possibilities to trap in better habitats, or near the coast.

The power supply just about lasts a summer night with a 20w blacklight. (~9 hours). For a couple of nights on the road, I'd swap from the blacklight to a battery UV led at some point during the night.
Both blacklight and UV LEDs seem to complement each other when run together, and is probably approaching the MV levels of light output.

pppppvvvv · Jun 12, 2023

Atropos said:
Just re-read this thread. I recently bought a LepiLED system that runs off a 30000ah powerbank. Very impressed so far whilst numbers of individuals are certainly lower the diversity if probably about 80-90%. So far have only run it in the Dry season here were numbers are far lower anyway but have had nights solely with the LepiLED with 120+species which for the time of year is excellent. I tend to run them together with an MV (take a honda generator with me) and find they compliment each other and bring different species in

Any results in optimal conditions with the lepiled?

Atropos · Jun 13, 2023

peter.jones said:
Any results in optimal conditions with the lepiled?

Oddly I was just thinking last week about updating this as the Wet season is over. It is hard to compare seasons here as the rain totals vary hugely and have a big impact. That said the last two Wets have both been good (the preceding 5 or 6 were classified as failed Wets due to the very low rainfall totals). Wet 21/22 had approx 3m of rain with the majority falling from Feb onwards, 22/23 has had over 3.5m most importantly though it has been steady and regular since early December (we almost got caught by this and only just managed to drive home from a holiday in UK as the road to my town is basically unsealed and the early rain made the usual 8 hour trip closer to 12 hours all of which was done in low ratio as the track was falling apart as we drove it). The number of individuals was down (peak 10k inds on the sheet on several occasions in 21/22 compared to peak 5k in 22/23) but diversity was much higher (good night in 21/22 150sp with one night over 200; in 22/23 200+ sp was not unusual and there were several nights over 250 species). A good comparison for the effectiveness of the LepiLED on its own was a series of weekends in Feb. On the first used both MV and LepiLED, on the second due to technical issues just LepiLED and then the next genny was repaired and so used both. There was a drop in diversity on the LepiLED alone weekend with a peak of just 210 species where as the weekends either side peaked at 250+ (huge caveat here in that I am still working on many of the photos and there are roughly 100 photos of prob 60+ species to be identified for each session but the proportions will probably stay the same). Also of interest is that the range of species changes with the LepiLED and there were 20+ species (haven't counted accurately I'm afraid) that only appeared with the pure LepiLED sessions, given how fickle moths can be and that it is only from one preiod the light source might not be the reason for this but my gut is that it is certainly a factor.

pppppvvvv · Jun 15, 2023

That's interesting. You probably get the most accurate comparison due to having such high numbers of moths.

BriLee · Aug 26, 2023

There's also a New LED light by Ento nets UK called a Podlight it consists of 2 uv,2 green and 2 blue Leds ,I have been using it in a disused upland quarry in the South Penines,I'm very impressed with it,I'm using it with a pop up insect rearing mesh cube,I've added some white vanes ,which definitely improve the trap for holding Carpet types, now,I've been using this set up for a month now,it is so portable used in conjunction with a 4800ah powerbank .I targeted 5 species of Moth,and so far 3 of the target species have come to the Podlight ie Confused,Tissue,Drinker plus noteable Local Moths Neglected and Heath Rustics,Anomalous. Regards Brian Leecy

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