Light Traps

(nothing herein is a paid advertisement, nor am I selling designs or traps)

One of the most indispensable tools for a lepidopterist is their light trap.  While collecting at a light sheet is useful (and fun), it does not provide the utility of a trap simply because it is impractical to remain attentive at a sheet for all hours of the night (I’ve only done it a few times!).  Any sufficiently designed trap is a force multiplier and will increase your catch 100 fold all while being much easier to deploy in the field.  No one could ever catch this many moths at a sheet in one night! (yes that bag is also full)

Moth Overload Grinter


For years I have purchased and used the bulletproof designs of Leroy Koehn at  I own a few of his traps and they have spent thousands of hours working overnight for me everywhere I have traveled to collect.  If you can afford his traps they are worth it – the vanes are indestructible and the ballasts have an integrated photoelectric switch.  The rain drains can also handle a monsoon, although I believe they allow for too much air-circulation and diminish the effect of your killing agent (usually Ethyl Acetate).  On the downside Leroy’s traps are bulky and expensive, so not practical to deploy in large numbers. BioQuip does have a more affordable option for a 12 watt DC trap starting at $160, however I do not like their rain drain design, bulb type, nor acrylic vanes; although the bucket can easily be modified if desired.


The quick and easiest trap is just a light on a bucket!  No vanes, no strange mechanism – nice and simple.  Actually I’ve completely abandoned the use of vanes lately since I notice zero difference with catch results.

8 watt bulb placed within the funnel

Top view of the 8w light

15 watt light held to a bucket with bungee cords


But if you’d rather stick to the old vein design here is what I’ve put together for a cheap-er version.  Like every other entomologist out there I have tinkered with my own trap design and have attempted to redesign the mousetrap.  Here is my proto-prototype vein design.  Any advice is welcome, and I would love to see other designs and share them here!

Grinter Moth Trap

The basic design is two PVC caps that snap onto acrylic vanes – the caps are connected by bungee cords that perfectly hold the vanes in place while allowing for quick and easy assembly and dis-assembly.  The vanes then fit tightly in a 10″ funnel held onto the 2 gallon bucket by shortened mini-bungees.  Any UV bulb can then be dropped into the vane assembly (in this case a BioQuip light).  The diameter of the vane opening at the bottom is slightly narrower than at the top, providing a very snug cavity for the bulb.  Cardboard egg cartons or towel padding has to be added to the bucket to provide insect resting area.

Cost: Bucket and vane assembly is  $56.37. (w/o tax) – the standard 15w light from BioQuip it is $60.70.  Total price is ~$117.

Advantages:  Lightweight, small.  The only limiting factor is the size of stacked buckets, about 12 traps require the same storage space as 2 rigid built traps.  Vanes collapse to be negligible in size, the smaller 2 gallon buckets are better suited to a less-abundant fauna but can be upgraded to 3 1/2 or 5 gallon sizes for appropriate areas (mounting the funnel onto a lid of a larger bucket is all that is required).  Broken vanes can be replaced in the field with cardboard or wooden backups can be prepared ahead of time.  Cheap!

Disadvantages:  Acrylic is not durable enough for long term use, the ideal material would be aluminum.  Joints on the acrylic had to be reinforced with strapping tape – thicker acrylic might be better….  The bucket and vanes are so light that it must be staked down in the field.  Poorly made by a non-engineer.


Now for more detailed specifications:

Supply list, purchased from your local “mega hardware store”.

2 gallon bucket $3.58

2″ x 2′ PVC pipe   $3.69

.093 – 20 x 32 Acrylic Sheet   $ 13.98 ea  (thicker would be better)

10″ funnel (from brewing supply store)  $17.98

1/2″ x 2′ PVC    $0.99

1/2″ PVC coupling  $0.25

mini bungee 8 pack  $2.47

fiberglass screen  $5.98 – for rain drain

small funnel (from auto-supply store)  $1.98

Plastic epoxy  $5.47

10′ of 4mm bungee cord – minimum order $20.  (left out of total, rope can be used for a cheaper cost)

Tools required:

Dremel tool for cutting grooves in PVC and acrylic

PVC pipe cutter – for both 2″ and 1/2″ pipes.

Acrylic/Plexi cutting knife  (helpful video for cutting)

Drill with 13/65 bit for holes

Safety glasses!


My favorite batteries for powering these 15 watt bulbs are sealed lead acid (SLA).  They are smaller, lighter in weight, are FAA approved for air travel, and don’t leak acid all over your car and clothing.  They are also pretty cheap.  If you explore your local battery suppliers you can usually find these for about $40.

For regular use I use this 18 amp-hour 12V battery:  $34.95 before shipping.  The 18ah rating provides a full night of light with enough buffer to extend the length of the battery for a few years.  The less percentage you can discharge a battery the longer it will last.

For international trips a 14ah battery is better.  They are slightly smaller and lighter and will provide about 7 1/2 hours of light before becoming exhausted.  Because you are fully discharging the battery they will not last as long.




28 comments to Light Traps

  • Jim


    Was wondering if you knew of something very portable and waterproof or resistant and battery powered?

    I live in an urban area and a dont have a power source near any kind of woodsy area.

    I would like to be able to setup something in the woods at a local regional park but worry about overnight rain. It rains infrequently here. The park is 20 miles from my home.

    Was thinking of something that involved a high power UV flash light.

    • The combination of a 15w UV bulb from BioQuip and any motorcycle/wheelchair battery will do the trick. I’ve used these in heavy rain without problem – I just be sure to cover the battery terminals with a tarp to prevent heavy water from shorting the connection. Moisture has never given me a problem with this gear.

      • Jim

        Thank-You! Do you just place the battery on the ground? Also what sort of trap should, I incorporate the bioquip 15 watt light into?

        • Yes – directly on the ground works perfectly well. As you see above I simply place the 15w bulb over a funnel on a bucket. No fancy gadgets – if you know or are afraid of rain you can build a rain-drain into the bottom with a small funnel. Placing a ping-pong ball within the funnel will act as a seal (but will float and drain water if it rains). Happy hunting!

  • Jim

    Thanks very much Chris! Just one last question and I will stop bothering you. When it comes to your light over the bucket trap do you have a funnel of some sort resting underneath the light and bungee cords and what is it exactly or where can it be gotten? Thanks!

    • Always happy to answer questions! BioQuip makes a very nice funnel that fits a larger 10g bucket (the funnel is a bit long, so a shallow 5g bucket doesn’t leave enough room in the bottom), the lip of the funnel seals perfectly to the bucket. It’s a bit expensive, so honestly *any* funnel over any bucket will get the trick done. Add a few egg cartons or paper towels to absorb any condensation and to provide the moths a hiding space. And the bungee chords just hold everything together in case a light breeze comes along or something – it’s good to make sure the light doesn’t fall off your bucket and ruin a night of collecting!

      • Jim

        What do you use to charge these batteries for the next nights hunt? Thanks very much!

        • Any variable rate battery charger will do, mine has a 2, 4 & 6 amp setting. When I’m not in a rush I charge at 2 amps to save battery longevity. 6 amps is fast but will cause faster degradation of the cells. You can pick these up at any automotive store.

  • Sebastian

    Years ago I made an incandescent light trap that worked pretty well in the UK ,and now I am starting afresh with a grandchild in Vermont.
    Are the bio quip bulbs significantly superior to say a cheaper bug zapper bulb? We tried just a white ryobi led lantern last night without too much success…would wrapping the lantern in blue tissue paper likely improve the attraction?
    Also the brewing funnels I already have , have a very long stem.i would like to,be able to,trap the largest moths. Do,you trim the stem a few inches shorter so the opening is larger? If so , to what diameter approx?,

    • The BioQuip bulbs are your best bet because they are built to withstand weather a lot better than a bugzapper light (that has to be removed from the case). Never had a bulb go bad in the rain! Wrapping a bulb in colored paper will only give you colored light, not the best spectrum for attracting lepidoptera. A UV light has a broadened spectrum peaking at 350 nanometers. The blue isn’t what’s actually attracting the moths, it’s the UV light we can’t see (blue is around 470nm). And I do trim down the funnel size to make it larger, but you don’t need it very big – an opening of 1.5″ is significant even for a very large moth!

    • security alarm system

      Thank you for the great information and interesting articles.
      Regarding the blacklight that you show that is 8 watts in the first picture, where do you get something like that? Is that DC or did you have to use an inverter? I see various blacklights on Amazon that are half the price of the Bioquip version but they are AC. I don’t mind paying for the Bioquip one (I actually have one for the regular blacklight setup) but would hate to buy something that can easily be stolen when unattended.
      Thank you for any tips,

  • Sebastian

    Thanks for the speedy response! So, is 1.5″ opening on the funnel big enough for even the larger silk moths ? (We were not so lucky to have those in England! Emperor moths notwithstanding )

  • Anton

    Hello Chris,

    Thank you for shearing this information! I’m wondering how you connect your 15 UV lamp to the SLA batteries? What type of wiring can be used?


  • Anton

    Thank you for Your answer, Chris!

    Now I have a 12V18Ah battery, a 12V battery adaptor with alligator clip and a 15W blacklight tube. What should I use to connect this blacklight tube to my 12V battery adapter – they are not passing to each other? (As you can see I’m not an electrician at all)))

    • Hi Anton- Did your black light come from BioQuip? It should have either a car-charger style plug (DC) or a regular house plug (AC). If you have the AC version perhaps it is best to return it for the DC version. Or you need an ac/dc converter so you can plug everything together. Or you need to run a power cord to plug your bulb into the electricity.

  • Good-morning,

    A couple of questions as I try to rig up some traps:

    Does funnel color make a difference? Are those metal (aluminum?) funnels/light casings good?

    I was just planning to go with a ‘light-over-bucket’ approach, do you find your catch a lot lower with those vs. the upright design?



    • I don’t think the color of the funnel makes a difference, but the metal ones from BioQuip are very nice (they fit a larger 5 gallon bucket). I think a dark or metal funnel keeps light out of the bucket and helps the moths settle down when they enter.

      I see no appreciable difference with the upright vs. flat over the funnel. I would encourage you to try different trap designs, but my traps at the LepCourse this past week (the only ones with bulbs flat across the funnel) caught the exact same number and types of moth as the ones with an upright design with vanes.

  • Garin

    Hi Chris,

    Thank you for the great information and interesting articles.
    Regarding the blacklight that you show that is 8 watts in the first picture, where do you get something like that? Is that DC or did you have to use an inverter? I see various blacklights on Amazon that are half the price of the Bioquip version but they are AC. I don’t mind paying for the Bioquip one (I actually have one for the regular blacklight setup) but would hate to buy something that can easily be stolen when unattended.
    Thank you for any tips,

    • Garin-

      The 8w above was wired by a friend of mine to DC, the bulb is something along the lines of this:

      My go-to light is the 15w DC BioQuip bulb as shown in the last photo. It does seem to pull in more than the 8w, and is pretty rock solid. And there isn’t much you can do to secure your trap other than do a good job of hiding it. If you’re in a higher-traffic area consider using a “dark” black light bulb. But you will lose a trap some day! In all of my collecting events I’ve only had one trap go missing.

  • Garin

    Thanks for the tips, much appreciated.
    Sorry, one other question. With the light trap, are you still able to collect large silk moths? What minimum size diameter is needed at the smallest part of the funnel opening in order to catch the larger silk months?
    I have never done the light trapping but when I see pictures of it, it almost seems like there are tons of small moths and never any big ones.
    Thanks again,

    • I also have been using the BioQuip funnel part #2851B. It’s expensive, but the best quality funnel I’ve been able to find. It fits perfectly on a 5 gallon bucket (12″).

      The diameter at the narrow end is probably 2″, and will allow for Saturniidae to fit. Think body size, not wing span. I’ve gotten good specimens of Citheronia, Hyalophora, Eacles, Actias, etc… However, bucket trapping is NOT the best way to trap large moths. Big silk moths tend to bounce around a light and settle around it, so in the morning you can often find more Saturniidae outside the trap than inside. If you only want big moths then consider getting a mercury vapor sheet rig.

  • Garin

    Thank you! Great information.
    I am planning a trip to southern Arizona this summer so will let you know how it goes.

  • Beth

    Thanks for your awesome site!! I have been looking everywhere for an affordable light trap option. I plan to have my father, who is skilled at wiring, build this for me.

    I don’t know if you still check this page or not..but! Are there any safety issues involved with leaving a setup like this in the woods overnight? I’m a worry wart and I could see me leaving my trap in my local public park overnight and not being able to sleep due to worrying that I’m currently burning down the entire forest 🙂

    I’m a field biologist who works with birds who has to take the summer off so I’m working with my moth obsession to fill up my time. I’d really like to start compiling some species data for the county I live in, and unfortunately my back yard is lacking in some key habitat. I’m itching to trap some local areas.


    • Hi Beth- you should take normal precautions when placing your trap to avoid dry plant material packed around the battery and ballast. I usually step down a little clearing or brush away plants if I’m placing the trap in dry grasses or leaves. The ballast gets a little warm but never would be hot enough to start a fire. The battery could potentially spark should it be disturbed, but use tight fitting alligator clips or bolts to attach your wiring to the leads. I’ve never worried about it and have trapped in the direst of California’s summers.

      Have fun!

  • quincy

    hi were can you get the light i want the light bulb and the thing you use to light it up an you give me links or places where you can get the light bulb + the thing you use to light it up thanks

  • Have you ever compared an actinic catch with a MV bulb? Everytime I do so I get ten times as many in the MV trap. Pain in terms of power sources though.

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