Friday, 5 June 2020

To LED or not to LED? That is the question.

I'm afraid this is a purely text only post with no pretty pictures.

For some time now I have been considering converting my Skinner's trap to LED.

I have always been shamefully aware, especially on winter nights, of 125Watts burning all night long to find nothing in the trap the following morning, not to mention the fossil fuel burning generator I use at group events, ironically where we are generally recording declines in moth numbers, attributed in part to fossil fuel burning induced climate change.

This has never really sat well with my conscience but then there appears not really to have been a particularly effective alternative to MV lamps ....... until now.

So, I am wondering about the pro's and con's of LED UV trap lighting.

It certainly improves mobility of equipment and efficiency of resources but does it actual work as well as an MV lamp? Are the results parallel to MV bulbs or do you get different results?

From a preliminary scan online, there appear now miriad ways of decorating your trap with UV LED's but it seems if you go down the DIY route you have to  calculate carefully the number of LED's, their output and quantity, layout in the trap etc to ensure an effective lure for moths without flattening the battery quicker than an iphone.

It is definitely a route I wish to go down so would be very grateful for any comments, experience or opinions anyone has on this subject before I take the plunge!

Cheers, Phil.


  1. Hello Phil - this is a very topical post as many people are looking towards being more green and I'll do my best to throw some light on it (well, maybe not LED, but we'll see).

    I run my Robinson 125w most nights at my home site and like you, back in 2016 I decided to look into the possibility of reducing my power usage by using LED or low energy bulbs.

    To give this initiative the most thorough test I decided to try these alternative bulbs throughout the whole year, during which time I tried various LED and low energy UV bulbs which all worked to varying degrees, but generally speaking I was disappointed with the results as many species which I would normally see throughout the year didn't show up and numbers were vastly reduced as well.

    The figures below relate only to macro moths recorded during the past 10 years at my home site and each year shows species recorded and then the moth count for the year.

    2010 = 307 & 22744
    2011 = 317 & 21715
    2012 = 295 & 16306
    2013 = 311 & 21225
    2014 = 297 & 16077
    2015 = 292 & 12483
    2016 = 229 & 4242
    2017 = 321 & 18824
    2018 = 313 & 24301
    2019 = 314 & 21495

    As can be seen from the figures above, the species count in 2016 was down by about a third and the moths recorded was down by about 70% of the average moth count over the last ten years.

    So what can we glean from this - do LED's work, well, yes of course they do, but from my testing during 2016 I can say that they didn't really come close to an MV bulb.

    Conclusion: -

    If your main objective as regards moth trapping is to be content with a reduced species count, then an LED setup would be fine. However, on the other hand if your objective is to see exactly what species are flying on your patch, then an MV setup has to be your best choice.

    Therefore if you're looking more towards a financial saving or being greener with a lower energy use I would suggest that you trap less (say once a week, instead of twice), but stick to the MV setup so that when you do trap you've got the very best potential to record as many species possible on your patch.


  2. Here's a quantitative analysis of four trap types (including ALS' 2x2w LED trap) in case it's informative:

    I've been rather disappointed with it but other people seem
    to get on OK with them.

    I agree with Peter that running less may be best option if you're concerned about carbon footprint. When attached to the mains I didn't think MV bulbs were particularly power-greedy.


  3. Thanks Peter and Douglas for your in depth information and advice.

    It looks live LED still has some way to go with development to the efficacy of an MV lamp. Too many permutations it seems for consistent recording compared to MV.

    So it looks like MV is what I will be sticking with for now.

    A bit worrying perhaps, is newcomers to mothing being drawn to the "greener" aspects of LED traps. Most websites selling LED traps appear to fail to point out the potential shortcomings and this could possibly lead to "normalised" local under recording being fed into county records.

  4. Yes, I think a lot of newcomers to moth trapping will be drawn towards getting a setup which uses LED's, which are obviously 'greener', but in the long run, in my opinion, they will be disappointed with the results.

    I think that a small battery operated portable trap, like a Heath which use LED's would be a good addition to anyone's trapping kit, as obviously this makes getting around with the trap far easier, but when it comes to your main site trap, stick with an MV, as this is where you will get a balanced overview of what species you've got at your site and where the majority of all the exciting rewards are going to be.


  5. We've got a battery operated LED heath trap. It definitely doesn't catch the same number of species as our MV Skinner, but does seem to attract different species. We were told when we bought it that it would work best where there was no light pollution. Glad we've got it, for the flexibility, but wouldn't be without our MV trap...