LIGHT TRAPPING: Who, What When, Where and How

[ash]

Hi to all - and Happy New Year!

I would like to start a discussion on light trapping. I have been having fun setting up a light and a sheet at night since I was a kid with extremely varied success - some nights a spectacular array of beetles and moths come in to the light whereas on other nights very few insects come to the light at all. Some groups of beetles seem attracted to the light yet there are groups which sit quite happily on a nearby twig (e.g. Buprestidae) and appear to pay no heed to the light that has set their distant relatives into a frenzy.

The setup we use at the moment is to run a 250 watt mercury vapour light from a generator. The light is suspended from a rope above a white sheet that is hanging vertically from a suspended line. Both the light and the sheet are held up by two metal poles fixed with guy ropes to tent pegs. Underneath the sheet is a groundsheet large tarpaulin to catch insects that do not land on the sheet. We find that some groups come to the light, some hit the sheet, some hit the tarpaulin and others are just attracted to the general area so regular general searches of the vicinity are important.

In my early attempts I always tried to get into deepest darkest rainforest and hung the light and sheet from nearby trees. A friend started the idea of suspending the whole thing from a free standing pole setup so that it could be out in the open where it would be visible from a greater distance and draw from nearby hills and rivers. He also added the groundsheet to make it easier to spot insects that do not land on the sheet. It appears to have greatly increased the 'catch' of insects we see come to the light.

One aspect I find very interesting is the variation between nights. In the last fortnight we have had nights where fantastic selections of beetles including Batocera, Rosenberdia, Xixuthrus, Phalacrognathus, Anoplognathus, Calloodes and Dorcas have come in, alongside a great inventory of moths. It seems that the night has had to be very dark, very hot and stiflingly humid. Just a week later with a longer period since rain and a bright half moon the same light setup seems to be attracting very few beetles. It also seems some things come early in the night and some come late. Some stay and some hit the sheet, hang around for a bit and then leave.

I am interested to hear if anyone will share their setup and experiences with position of the light sheet, altitude, rain, humidity, temperature, time of night, variables like the moon phase, and what types of insects come to lights.


Ash

[rjb]

I've used UV light to collect beetles for many years. My observations agree well with yours for variability. I live in a dry area of the US, New Mexico, and UV light in the yard every night. The number and variety of insects varies with temperature and rainfall very dramatically, warmest and wettest is best. Some of the rarest beetles have come at extremes of our season though, early spring or very late autumn. I have used both 150 watt Hg lamp and 40 or 15 watt lamps and find little difference in collection effectiveness (this is different from many others who find higher wattage is better).
Once in Australia in the Northern Territory, I collected >30,000 beetles (lots of variety but very large number of a couple small species) with a 15 Watt blacklight. I set the light over a flat container of water with a little detergent to break the surface tension- leaving the light on all night and sorting in the morning.
In dry areas like AZ and NM, the beetles collected from a night of UV lighting can greatly exceed the entire day of hand collecting, and the species are different of course. Nothing beats UV lighting in the tropics, Amazon or SE Asia or Northern Australia for intensity of insect experience! Anyone who is not an insect lover can be overwhelmed.
Rick

[mikelock34]

I hammer three rebar poles in the ground about six feet or so apart. I tie a wire core clothes line tightly betwween the outer two poles. I tie a 1000W MV light to the top of a twelve foot high pole in the center of the set up. I tie a large sheet between the two outer poles. I hang UV lights on each side of the sheet with the bottom of the light being pulled away from the sheet to get greater surface area of UV light on the sheets. This set up is very portable with the long pole hanging from the window of your car or you can just cut a small tree down each time to set up the 1000W MV light. Frosted or unfrosted bulb never seems to matter. This set up works exceptionally well every place I have used it. It can get a little overwhelming using this set up in the tropics. Typically, anyone collecting nearby leaves and sets up somewhere else as the bugs tend to come to this set up over other set ups that I have seen used. People mention that females of some moths and other insects will land far out from the sheet and never come into the sheet because the light is too bright. I have not found this to be true. We have had to stand in front of the lights on the sheets to stop Titanus giganteus from smashing the lights as they come blasting in and female Copiopteryx and other female moths come righ in to the sheets typically.

Forgot to mention that I duct tape six foot high wooden poles to the outer rebar poles to tie the sheet to. You can cut small trees for that too though.

[Deleted]

I constructed a portable light sheet rig using 3/4 pvc pipe. It can be assembled in
less than 10 minutes. I use two UV fluorescent bulbs in a standard shop light fixture that is attached to the frame of the light sheet. Last year running it in my back yard I collected almost 300 beetles and about 200 moths. Given the fact that this thing cost less than $50 to make I couldn't be happier with the results. I feel that I got a good ROI.

Joe

[compsulyx]

Hi all and Happy New Year, all the best for 2015 !
I'm most a moths collector and I'm using a light trap with different sorts of lamps. I use a 125w MV lamp + a 40w actinic fuorescent tube for most of the trappings, and after years, I think it's the most efficient. Generally I use this on the edge of forest, but when I'm in very openend areas, I add a 250 w MV bulb to increase the power, so I can attract more specimens. If I'm into the forest, I try to use the 125 w or a 80w if I'm really into deep forest, because I've noticed that if the lamp is too strong, many specimens are hanging on trees far from the white sheet, and it's a lot of work then to find them into the bushes on the early morning, most of the time impossible if they are too high.
I've never used a 1000w lamp....seems to be very strong, but I'm opened mind and perhaps I could try just to see the difference, why not...
Problem then is the quantity of gasoline for a night. Most of the time I'm running the lights all night, to make sure to have a complete survey and maximum species. This point is important too I guess because I've noticed that many persons are running their lights only first part of night and then stop. I think it can be ok for coleoptera which come most on early everning, but.....not all species....For example during my last light trapping I got very rare Cerambycidae after 1 am, nothing before. Same for moths, many rare species are coming to the light later in the night, so I think to be as afficient as possible, a light trap should run all night.
Joe, how long your system is running ?....Only a few hours ?....I'm looking for a portable system which could run with two 8w tubes or a single stronger tube, when I go to isolated sites, where it's impossible to bring the generator, etc....if someone can give us some tips to make a system which can run all night, that would be fantastic. Many thanks in advance !
Thierry

[mikelock34]

There is no place that I cannot carry a generator into. If you need to use a generator that can be carried in one hand, just get one of the small 1200W, 1500W or 2000W generators that are readily available on the market.

[compsulyx]

The smallest I've found a few time ago (second hand) was a HONDA 350 watts only, very small. But shipping cost from US was higher than the cost of generator !....and they don't sell it here in New Caledonia. Also, I've read that they stopped to make it now, you can only find second hand generators....
Then the Suzuki 750watts seems ok, but very expensive and a bit heavy. I really need something not heavy, just 5-6 kilograms, not more. I will try to ask to Japanese friends to find one...
Thanks for tips.
TS

[ash]

Thanks for the tips.

That is a good idea adjusting the power of the light to match the draw area, although getting a selection of MV lamps isn't going to be that easy here - well we have a couple of weeks of high moon to track some down before the next good nights. Fortunately there are still lots of great places here that you can access with a 4WD so the weight of a generator has not been a problem yet. That tiny Honda generator you spoke of is an excellent piece but no long on the new market here either. one experience we have had with power leads is rodents chewing the plastic coating off!

cheers

Ash

[lucanidae25]

I came up with this set ups when I was traveling and collecting overseas. 12x 12V 8W dc fluorescent light tubes that powders by 8x AA 1.2V rechargeable batteries for each light tube. 96 AA batteries to powder 12x lights and takes 12 hours to recharge them all. wights 7-8Kgs all together,waterproof and no generator. I also had one 100W MV, one 250W MV and one 500W MV glows with 15M extenstion cord, uses directly from powder points where ever I stayed.

[Deleted]

Joe, how long your system is running ?....Only a few hours ?....

Here is a photo of the light sheet that I use. I posted a picture of it in another thread on here somewhere.

I usually use it in my back yard that at the end of my property that turns into a large woods. I like to run it all night when I can weather permitting. I have get up early for work so I check my sheet and turn it off around 4:00am. If I think its going to rain while I'm gone I just take the light fixture off and bring it in along with the power cords.

[leptraps]

I normally try to remain silent on these subjects. However, I will tell you what I hear from users (And I hear a lot).

Two 40 Watt 24 or 48 QBL (368) and one 250 or 500 watt Mercury Vapor Self Ballast clear. These are the most often purchased combinations of collecting lights or bulbs from Leptraps.

I personally believe in lot's of power. My personal set-up in 88" Height X 82" Wide Frame & Sheet Assembly. The frame and sheet assembly are all aluminum tube of collapsible construction (It is secured with 8 set screws) I use two 40 Watt 48" QBL and Two 40 Watt 48" BLB and the 250 Watt MVSB Clear. I also use Mercury Vapor Spot lamps, especially when on a prairie.

When surrounded by or deep within a forest, I switch to 100 MV with Ballast. I point the Spot lamps into the forest. I have experience some fantastic night of collecting. And when in Arizona in August, prepared. It is unbelievable

[bichos]

Jan 3, 2015 0:34:39 GMT -8 lucanidae25 said:

I came up with this set ups when I was traveling and collecting overseas. 12x 12V 8W dc fluorescent light tubes that powders by 8x AA 1.2V rechargeable batteries for each light tube. 96 AA batteries to powder 12x lights and takes 12 hours to recharge them all. wights 7-8Kgs all together,waterproof and no generator. I also had one 100W MV, one 250W MV and one 500W MV glows with 15M extenstion cord, uses directly from powder points where ever I stayed.

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Finally some pictures, thank you.

You don't use black light tubes?

[lucanidae25]

Only 2 black lights

[mothman27]

Do Metal Halide work as well as Mercury Vapor? As is as many moths and as many species?
Thanks,
Tim

[leptraps]

Metal Halide bulbs produce no UV. However, some Metal Halide bulbs produced in India were actually Mercury Vapor. These are no longer availible.

There are very few manufactures of Mercury Vapor bulbs that are self ballasted and clear or non-coated. Although Mercury Vapor bulbs are still available, most are Metal Halide hybrid bulbs.

I have recently learned from my supplier that they will continue producing 160, 250 and 450 Watt Mercury Vapor bulbs through 2016.After that they will no longer be able to get some of the components.

I current have all three in stock.