Any ideas of how to improve this light trap?

[olletott]

Hi!

We are a group of amateur entomologists doing a small field project on community composition of moths in Sweden. We have built five light traps that we have tested for one night. Out of the five traps only one managed to catch a moth, and we suspect this has to do with probably low efficiency of the trap since we know there is a lot of moths out at the moment.

The traps are a blend between a window trap and a light trap, consisting of a plastic pane standing vertically on top of a bucket (see linked pictures). In the middle of the plastic pane there is a small UV LED-light (390 nm) powered by a powerbank. The light source might look very small but it is incredibly bright. In the bucket we have a funnel that helps collect the moths. There is also an aluminium cone below the lamp to help reflect the light outwards.

The design was made to be very cheap and easy to build, but we don't see why it wouldn't work. We however have very limited experience with light traps and would be very thankful for any ideas on how to improve their efficiency

Link to pictures:
drive.google.com/drive/folders/1EnVXnjjqUyfWAg4oGxuRE2tmaMUCYu_u

[vabrou]

olletott, My wife and I have operated self-designed, automatic capture high-wattage light traps every day nonstop for the past 55 years (1969-2024). Turned them on when I was 20 years old, now I am 75 and we just last month turned all of them off. Our bodies made us turn them off. During this time we designed and fabricated a total of around 500 automatic-capture insect traps of many purposes for various insects which operated 24 hours every day of every year. Automatic capture meaning one does not have to be present to operate the traps. We never turned off any of our traps for any reasons. You will eventually discover that some species may only be active for 20-30 minutes each day, e.g. at 0400 hours, and if you don't have a working trap when they fly, you will never see them.

I find it most incredible that you captured only one moth using 5 traps. Obviously, there is something very wrong with your traps or your methods. Our best one day quantity (24 hours) of insects here at our home location amounted to about 124 million insects of all types, but we used hundreds of insect traps to capture this massive quantity. Here is a freely accessible link to a pdf I put together about 10 years ago illustrating just a few of the 500 insect traps we operated here. We logged about 51,000,000 trap hours of all types of insect traps over the 55 years, and captured numerous billion of insects.
www.academia.edu/9665262/Images_of_some_of_the_insect_traps_designed_fabricated_and_operated_by

The first thing I see is a major problem is that your light source is attuned to 390nm. Get rid of the 390nm. Change your lamp wavelength to one emitting 365 nm. Send me a jpg or two of your traps. Over the past half century most of our light traps used combinations of several lamps e.g. usually four 15-watt fluorescent blacklights along with mercury vapor lamps of varying wattages, e.g.,275 watts, 400 watts, and 1,000 watts. Sometimes we added additional ballasted and self ballasted UV lamps of other descriptions onto the light traps as well. Key to accomplishing all of this massive collecting automatically is the design and use of a collection chamber attached to nearly all of our 500 traps. Now our light traps operated every day at the same locations because the collection chamber on each light trap was quite large to nightly capture hundreds of thousands of large and small delicate moths in pristine condition. Some semiochemical lure traps e.g., for clearwing moths were easily transportable, but these too had collection chambers designed into each trap. Final note: all of the captures in our automatic-capture traps were quickly dispatched using NaCn. Using our traps and methods we discovered over 400 species of moths new to science. About 700,000 insects with my labels on them have been distributed to museums here in the US, and museums and major collections across the world. Additionally our master research collection of mostly Louisiana moths is housed here at our home and those amount to an additional 500,000 specimens and this quantity is destined for eventual placement in our Louisiana State Arthropod Museum.

Vernon Antoine Brou Jr. and Charlotte Dozar Brou E-mail: [e-mail]

You may find some useful information in the pdf we published in 2022 illustrating some of our lifelong discoveries we made over the past half century here in our state of Louisiana. Her is that link:   www.academia.edu/96051394/ABITA_ENTOMOLOGICAL_STUDY_SITE?sm=b

[vabrou]

olletott, I have looked at the five photos you provided and immediately see several problems.

1. Your light source should be placed about 1"-2" facing upwards above the level of the funnel rim.

2. You have all of those unnecessary parts above your light source which is blocking a huge amount of your light rays emanating from your light source, remove all of that unnecessary clutter.

3. You also have something you absolutely want to get rid of (the reflective cone). Your understanding of how a light trap operates is completely wrong. You never want to reflect any light from your trap, NEVER !!. Insects are attracted to your light source at the area of the funnel, never reflect any light rays from a trap. Do the opposite of reflecting, e.g. unobstructed light source placed just above non-reflective surroundings (funnel).

4. I see you use clear plexiglass. This also promotes reflecting light emitting from your lamp. You will note in the examples of every one of my light traps in the link I supplied all have one color, that is flat black, which never reflects any light. Your goal is to have the insects go to your light over the funnel, not somewhere else you are reflecting it. My light traps were fabricated out of galvanized sheet metal and all external surfaces are painted flat black. The traps I fabricated over 50 years ago are still in excellent shape still operating to today. Of course the ballasts, starters, lamps, tubes, bulbs all wore out and thousands of lamps and tubes and these items were replaced many times over the past half century, this is normal and expected.

I have no experience using LEDs. Insect light trap colors were investigated for more than 100 years, and if lucky and persistent, you can find some of these studies in our scientific literature.

So move the light source much closer, centered over the funnel, paint everything flat black, and remove everything above blocking your light rays. Does your lamp operate in pouring rain? My light traps operated through many thousands of hours of torrential down-pouring rains for 55 years here in my state of Louisiana, including tornadoes and hurricanes, snow, freezing temperatures, etc. they were never turned of for 55 years for any reasons. Our high-wattage bulbs/lamps were unaffected by rains, as the glass envelopes are made of borosilicate glass which resists thermal shock (cold rain hitting a very hot lamp). The lamps and bulbs did not need any type of rain/snow protection and consequently the attracting rays were emitted in all planes surrounding the trap except for under the trap. You will note all of my traps have the fluorescent lamps vertically mounted above the funnel and the fully exposed high-intensity discharge lamps unobstructed facing upwards above the fluorescent tubes. The high wattage lamps bring in the hordes of insects to the trap and the 365nm fluorescent tubes between the four baffles above the trap funnel guide them into the funnel.

I should mention that in the light traps we designed and used, the rains entering the funnel were collected and immediately expelled from the inside of the collecting chamber.  Our light trap collecting chambers consisted of more often three pull out drawers, each having different sizes of screen bottoms to protect larger specimens from damaging the smaller specimens.  And the automatic rain expelling device was just below the apex of the funnel cone inside of the collection chambers attached to the upper pull out drawer.

Vernon