Light trap tips

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Light trap tips

Postby donaldsmith » Sat 12 Mar 2016 14:39

Nothing in the trap last night although it seemed very mild and only light drizzle .... before the season gets properly underway, I have a few niggling questions that I wonder if others might have an answer to.

1. Does the height of the trap matter - should I put it on a table for example rather than just on the ground
2. Should I put it as far from obstructions as possible - buildings, trees for example? Do different spots in the same garden have different fauna?
3. Should I put a white sheet underneath to increase the effectiveness of the light? Some of my best finds have been outside the trap or on the grass nearby - would a sheet help attract and spot these or will I just feed the birds?
4. Timing. When do the moths arrive - is dusk an important time to have the trap going and then once it is dark is that enough to sample what's about, or can you just put it on after dark and leave it going all night and get the same results?
5. Do you look at the weather forecast before deciding whether to put it out (wind, temperature, rain) or is success unpredictable - I suppose this changes through the year too.

I suspect that these questions were all answered long ago when light trapping first became popular, but I don't know how to find the answers! Experience or references to experimental evidence would be most welcome.

While I am picking your brains, I tried sugaring on half a dozen occasions last year with treacle, brown sugar and beer .... but not a single taker. Do you have to make it fresh each night (or week) and has anyone a good recipe they might like to share. Some old moth books rave about sugaring and the different variety of moths that it attracts.

Thanks!

Donald
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Re: Light trap tips

Postby DonMatthews » Sun 13 Mar 2016 11:14

Hi Donald,

I don't have enough experience to comment on your moth trap queries but like you I have been puzzling over sugaring. I started mothing in the summer of 2014 by experimenting with sugaring and had sufficient success to induce me to buy a trap and take it up as a serious interest. However, in 2015 I had virtually no success at all with sugaring. Had that been my experience in 2014, I probably would have given up on moths from the start! As far as I am aware, the only difference between the sugar I used in the two years was that in 2014 I used Newcastle Brown whereas in 2015 I used Guiness. The latter mix had less smell to it and perhaps it needs to be really smelly. This year I'm planning to try Newcastle Brown again to see whether the nature of the beer makes a difference.

Don Matthews
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Re: Light trap tips

Postby MarkCubitt » Sun 13 Mar 2016 19:10

Hi

Yes, many questions and attempted answers to these areas. No "correct"

1. Does the height of the trap matter - should I put it on a table for example rather than just on the ground
>> A trap higher up is certainly supposed attract more moths, but the challenge then is whether the moths will get up to the light. Some species such as geometrids may not have a problem, but some noctuids will struggle. Mark O'Brian at Hadfast always put his trap on top of a picnic table, but not sure whether he tested the alternative. You could try alternate trap nights for a year and let us know?!

2. Should I put it as far from obstructions as possible - buildings, trees for example? Do different spots in the same garden have different fauna?
>> Not necessarily away from obstructions. It depends on the layout of the garden and obviously you want the light to cast over a reasonable area to attract passing moths. "Obstructions" such as a white wall can be very effective 'traps' (see the next answer). Different places in the garden may be more or less effective for catching, but won't really affect the species you catch (unless you have a ver large garden!)

3. Should I put a white sheet underneath to increase the effectiveness of the light? Some of my best finds have been outside the trap or on the grass nearby - would a sheet help attract and spot these or will I just feed the birds?
>> A white sheet will attract moths in its own right (as with a house wall). Some species appear to prefer this rather than going into the trap. I use both dark brown and white sheets with a view to doing an analysis sometime about how many moths are caught inside and outside the trap, but haven't done so recently. Whether you use a sheet or not, but particularly with a white one then you should be out before the birds...

4. Timing. When do the moths arrive - is dusk an important time to have the trap going and then once it is dark is that enough to sample what's about, or can you just put it on after dark and leave it going all night and get the same results?
>> Apparently, on average there is a bit of a lull in the middle of the night with higher numbers early and another smaller peak later. Some species are well known for only being caught late in the night.

5. Do you look at the weather forecast before deciding whether to put it out (wind, temperature, rain) or is success unpredictable - I suppose this changes through the year too.
>> Yes, I certainly look at the forecast. The forecast is often wrong, particularly the minimum temperature which is frustrating. If the forecast is correct then predicting a good (or bad) catch is maybe 70-80% accurate. Mild, overcast calm, humid nights being best and especuially if it is the first such night after adverse conditions.

I have had some success with Sugaring, but not often. It is less predictable than trapping apparently. I am not really a wait around and see type of observer and so traps suit my psychology better. This I haven't persisted and investigated enough.

Mark
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Re: Light trap tips

Postby GeoffMorgan » Mon 14 Mar 2016 22:07

Great thread - I have enjoyed reading this.

I'm running the trap again tonight and so far it is another blank - haven't had a macromoth yet this year and I think it is a bit cold now.

My only advice based on this year is don't run a trap until after the 14th March... and maybe later!
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Re: Light trap tips

Postby MartinFinnigan » Tue 15 Mar 2016 14:09

Hi,

My tuppence: I had March Moth and 2 x Hebrew Character in the skinner trap in Edinburgh this morning and Dotted Border on the house wall for the last few days. Also trapped Small Quaker, Mottled Grey and Dotted Border in Perthshire at the weekend. In each case the trap was placed before dusk and on all night.

For interest, the Perthshire moths were in an experimental portable trap I made from a water cooler bottle which seems to work quite well. I'm also working on an LED light source that generates a range of wavelengths from UV upwards. I can run this from lithium ion batteries for portability. Problem is that it is so bright I can't possibly test it in town!

If anyone is interested I can provide photos of each design and can update in due course regarding both the bottle trap design and the LEDs.

Martin
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Re: Light trap tips

Postby MarkCubitt » Tue 15 Mar 2016 19:09

That would be interesting about the LED lights. I had a similar idea a few years ago and used UV LEDs and white ones. The former didn't have very high output and probably neither we as powerful as todays ones. Just having completed it I thenm heard that others had tried LEDs without great success so I lost heart a bit and never really tried it out properly. If your works and the LEDs' efficiency means that there is a low power draw then it could be a very nice solution.

Good luck
Mark
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Re: Light trap tips

Postby sbird » Sun 26 Jun 2016 00:47

Another tuppence worth? Though replies look excellent.

I've recently returned to moth trapping, and your questions prompted me to dig out my A level biology project. The subject was time of nocturnal moth flight, and I did a lot of reading around the subject, albeit in 1986!

1. Height of trap. This may be important. One species is documented as being most abundant at 30ft. (I wonder how the Edinburgh council rooftop trap is faring?)

2.Obstructions. These may reduce catch, though effect will vary with factors such as species, flying habits etc.
Remember how moths are drawn in to the trap...they navigate using a distant light source eg the moon, by keeping the same facets of their compound eyes illuminated, so they fly in a straight line. When the light source is near, the same mechanism draws them in, in an ever-decreasing spiral, until they hit the baffles and fall into the trap. (OK, it's a bit more haphazard, maybe due to confusion and attempts to flee the very bright light). If the"baffles" are further out, the moths may stop sooner, and have more opportunity to head off away from the light.
Obstructions may mean that the trap is not seen by moths further away, so the area from which they are drawn is reduced.
They may also be distracted by other lights, depending on intensity and wavelength.

3. Sheets. I don't know, as I haven't looked into these. When I used a Heath type trap, I found maybe 10% of my moths outside the trap. A sheet would have made this easier, and maybe a light-coloured sheet would have attracted more. As Mark Cubitt says, it's best to be up before the birds! With my current mercury vapour trap, I don't seem to be finding many moths outside the trap,even though I'm up before the birds.

4. Timing. My project involved trapping for 15 consecutive nights in July in North Antrim, dividing the night into 3 equal trapping periods, with short intervals between to remove the catch, which was not released in the vicinity of the trap that night. The vast majority of moths were caught in the middle period. (However, the Map-winged Swift was caught only in the early part of the night, and micro moths were caught throughout the night, but I was not able to identify these). However, it is noticeable that there are a lot of moths out at dusk on a warm evening, though few around dawn. It seems likely that factors such as temperature, humidity, food availability and pheromone dispersal will influence time of flight. These factors together with the ratio of artificial to ambient light, will affect the efficiency of the trap. A stronger trap may attract more crepuscular fliers.
And remember that some moths, especially geometrids, do escape. So it is worth sealing the trap and analysing the catch in the cool early hours.

5. Weather. My observations entirely agree with Mark Cubitt 's. A nice mild calm muggy night, when there hasn't been one for a while, is perfect. And then there is the problem of a large lively catch, especially when the Large Yellow Underwings emerge. Any hints for that problem?

Sheila
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Re: Light trap tips

Postby rogerfellows » Thu 30 Jun 2016 23:32

My two penn'orth as well. I like to have the trap lit as dusk begins or before. Remember the ones under the sheet, so tread warily. Having your net handy is a good idea, Old Ladies, for example will often visit and depart. I have left moths in the trap when checking late on which have not been there in the morning. I've taken to a walk round the garden when nearly dark - netted a common emerald the other night which was not around in the morning. If I had a suitable location without vegetation near I would use that to make spotting easier. A proper daylight inspection can yield things you did not see in the gloaming. At work I use a table draped with a white sheet and do not think it inhibits the catch. Roger
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Re: Light trap tips

Postby rogerfellows » Thu 30 Jun 2016 23:36

The lively catch problem I think can only be solved by making a large netting 'tent' to put over you and the trap before you start the count. I bought the netting two or three years ago, but have not yet made the tent. :oops:
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Re: Light trap tips

Postby georgehogg » Mon 01 Aug 2016 22:21

Maybe I haven't scanned every line of this thread,but I don't see any prominence being given to nectar sources.
Where bees and other pollenators gather by day,so moths will take over at night.
The garden where I trap has a succession of attractions such as red valerian,catmint and teasel.
I trap in amongst whatever is the main draw at the time.
Certain this approach makes a massive difference to success levels.
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