zine: DIY moth bucket trap

I made a mini-zine! You can print it, fold it, and share it with friends to spread love of moths. Download and print the zine from the link below, or buy a physical copy from my shop! Then read on to read detailed build instructions.

I've been using a bucket trap for moths over the last few summers with great success. Bucket traps draw in the moths overnight with a bright light, which disorients the moths and sends the clumsy ones into the bucket through a funnel. They rest in the bucket until you open it in the morning. No need to stay up late!

There are many great tutorials out there about how to make moth traps, but they vary by complexity, budget, and DIY ability. I wanted to create a Minimum Viable Product bucket trap that required easy-to-find parts, as cheap of a budget as possible, and near-zero handyman skills. I want to say up front that I am not an entomologist, not even an intermediate-level moth identifier, but every moth bucket morning feels like Christmas!

Here is what I have assembled. It is a no-kill, no-skill project that can be assembled in under an hour. You might already have half of the supplies in your closet.

supplies

tools

• Permanent marker
• Utility knife

supplies for the bucket:

• 5-gallon bucket lid
• 5-gallon bucket
• 8 inch plastic funnel (found at brewing supplies stores or auto shops)
  • You may need a handsaw instead of a utility knife to trim the funnel if the plastic is thick- keep this in mind!
• A few empty paper egg carton halves for moths to rest on
• A brick or similarly-weighted stone

supplies for the light:

• An A19 LED UV black light bulb
  • The stronger, the better.
  • It's worth considering the wavelengths- more reading here and here about how 365nm is ideal- but do not get caught up in the details for your first build if you want to go cheap. Most people start by using UV party blacklights.
• A corded light socket
• Lampshade ring with 8-10 inch diameter
  • The cheapest option is to thrift a lampshade and remove this part!

let's make it!

step 1: assemble the bucket

The bucket has two parts: the lid, and... well, the bucket. Start with the lid.

Place the large end of your funnel centered on the lid, and trace the edge onto the lid with a marker. Then use your utility knife (or similar cutting tool of choice) to carefully cut out a hole approximately a 1/2 inch smaller than the traced outline. The funnel should nest into the hole, supported by the cut edge.

We want the the small end of the funnel to be large enough to let moths in, but not large enough to let captured ones escape. Most guides recommend trimming the funnel down so the small end is 1.5-2 inches wide.

The bucket itself requires no alterations. Place the weight (stone or brick) in the bottom to stabilize the bucket, then add 2-4 egg carton halves for the moths to rest on and hide in.

step 2: assemble the light

Put the light socket into the small ring of the lampshade support, then screw the bulb into the socket. The bulb should be pointing towards the large ring so when we place the lampshade ring on the bucket lid, the bulb is pointing downwards.

step 3: put it together

Put the lid on the bucket, make sure the funnel is nested flush in the lid hole, and place the lampshade ring + light onto the lid. Plug your light into a power source, and you're ready to go!

step 4: using your bucket trap

I set out my moth trap around dusk as the sky is getting dark, turn on the light, and leave it until morning.

Conditions are very important for a successful moth bucket. You want to set up your trap on a warm (the hottest nights are the best), humid summer night without strong wind. Ideally, the moon is small, below the horizon, or hidden by cloud cover. Being in an area with lots of natural habitat is ideal, but even urban areas can have great mothing!

First, I thoroughly check the bucket exterior and the ground nearby. When visiting family in Michigan over summers, I always bring my moth trap with me. I almost always find at least one or two huge Polyphemus moths sitting right on top of the bucket in the morning!

Then I very carefully open the lid to glimpse what is inside. I place the lid back on the bucket as I take out the egg cartons one-by-one, checking every crevice and bump of the cartons for moths. Avoid bumping or shaking the bucket, which can cause moths perched on the walls to fly off and escape before you can observe them.

Each time I find a moth, I take a photo with my camera or phone, which is later uploaded to iNaturalist, the world's largest community science database. I take photos of all the other species that I find as well!

This moth trap is not weather-proof, so I do not recommend putting it outside with rain in the forecast as-is. Read the upgrades section below for ideas on how to waterproof it a bit.

troubleshooting

So you woke up, rushed out the door, and opened the lid to find.... nothing! What happened? The most likely problem is that the bucket was placed outside in unideal conditions.

Light pollution is the first potential culprit to consider. Turn off exterior lights and try to place your bucket somewhere dark. Unfortunately, my light traps in our specific urban backyard have never significantly attracted moths, even though they work great in other urban and rural locations. Both of our next-door neighbors have extremely bright, unadjustable garage lights that my my traps simply cannot compete with.

Cold temps and wind are the other two most common problems in my experience. Moth visitors tend to drop off when nighttime temps are under 65 degrees F, and a stiff breeze can keep them grounded.

It's also worth making sure your bulb is quite close to the funnel, the lid is on tight, and there are no large gaps between the funnel and lid.

If you're still mothless, upgrading your light source is the first thing to experiment with. The A19 bulbs are convenient and cheap for a budget build, but they won't be the most effective option out there.

upgrade ideas for your bucket

• $0-$20
  • My number one cheap recommendation is to hot glue the funnel to the lid. (Do not use tape on this project. The moths WILL find any sticky edges or upturned corners, and the results will be sad.) This fills gaps through which the moths can escape, and it makes the lid easier to handle.
  • Cut slits into your lid so you can zip-tie the lampshade ring to the lid for stability.
  • Drill some SMALL holes in the bottom so your bucket doesn't flood in case of rain. (I generally only recommend using this bucket design on dry nights or under a protective overhang.)
  • Waterproof the light by cutting the top off of an empty 2-liter soda bottle, slicing three slits for the lampshade arms, and placing it upside down on the light. These bulbs get hot, so don't let the plastic touch the bulb.
• $20-100
  • Experiment with different light bulbs. Or add more! Many people report success with bulbs for reptile setups, which require a different light cord.
  • To go mobile for cheap, get USB powered light sources and a phone battery.
• $100+
  • Upgrade your lights to the next level.
    • Get a waterproof, professional-grade 365 nm + 395 nm entomology light for about $90, and just hang it above your bucket with a cheap camera tripod. (This is my ideal setup. If you have the money to spend, I recommend doing this instead of the bulb + lampshade ring setup from the very start.)
    • Mercury vapor bulbs, the gold tier of the insect-attracting world, are scarce but still available on eBay. They will require a different mount than the lampshade and strong power source.
• Go fully mobile with a portable power station.
• Skip the build and buy a prebuilt bucket trap made just for mothing (although this is not in the DIY-spirit, I think it's worth knowing there are pre-build options out there!)

other moth trap build styles and guides

There are a ton of forum threads, blog posts, and professional guides on how to make different types of moth traps. Read through some of these links below for inspiration!

Budget Bucket Moth Trap

Budget Bucket Moth TrapUsing light traps to attract moths is a fun and effective way to find out more about moths. In order to encourage more moth recording East Scotland Branch have started a Budget Bucket Moth Trap initiative. This aims to encourage new moth trappers and also those who have not trapped using a mobile trap in habitats away from gardens. We have designed a simple moth trap using readily available components that allow the total cost to be kept low. It is not going to be as effective as more expensive, professional Robinson and Skinner traps with MV bulbs, but is small, light and a good way to get going. The trap based on a 20 litre bucket with a well fitting lid that can house a large household funnel. There are two lighting options that are both water tolerant, and avoid the cost and complexity of vanes and a rain cover. We plan to run introduction to moth trapping workshops at which participants will be able to assemble their own trap based on pre-built parts, but we thought it would be worthwhile to publish details of the design and construction of the traps should others wish to make their own.The two light options that have been designed are shown below.Compact Fluorescent The first trap option is based on a compact fluorescent bulb that runs off the mains. The wattage of these bulbs, of around 20w, is low enough to also allow the use of a cheap 12v inverter which can enable mobile use too. Two different types of compact fluorescent bulbs are recommended, one an actinic and the second a full white spectrum with up to 40% UV content.See how to make the light for this trapSee how to make the bucket for this trap LED Strip LEDs are creating a lot of interest and are increasingly being used for moth trapping. They are a relatively new introduction and there is still much to learn about them. LED strips provide a relatively easy way to allow a moth trap light to be made and have had good reports from moth trappers. So far it seems that some LED setups can approach those with fluorescent bulbs in some conditions, but often with different catch composition although seem to be less consistent in terms of moth numbers attracted.See how to make the light for this trapSee how to make the bucket for this trap Batteries and power 12v based power for lighting is a complex subject. Lead-acid batteries are not cheap, are heavy and have limited life if discharged and recharged too much. There are some that are designed to cope better with this charge cycling but even so have a limited life. The main alternative is to use one of the varieties of Lithium battery which are lighter, have longer but not infinite lifetime, but are even more expensive. Lower capacity batteries are cheaper and lighter, but won’t keep the light on for as long which can be a problem particularly in the darker months of the year. When calculating the capacity (in ampere hours (AH)) then lead acid batteries should not be drained to less than 50% capacity. Lithium batteries are more tolerant of more of their charge being use capacity being used. The compact fluorescent bulbs are mains AC powered, but there are products, called inverters, that will convert from 12v. We have successfully used these 75w inverters for over 10 years. A simple crocodile clip to cigarette lighter socket converter allows attachment of the inverter to a battery or a more sophisticated arrangement with a light sensitive switch as illustrated here is possible. The inverter must be kept dry. Note that the inverters are designed to work from car batteries which are actually up to 14v and so cheaper lithium batteries such as those mentioned below will drop their voltage below 12v as they discharge and the inverter can, or will, switch off.USB power banks and even car jump starter packs can be used. The former, particularly, are often not compatible with light sensitive switches. The USB ports are also only 5v rather than 12v, but for 10w or lower lighting a step-up converter can be used. See the LED light page for more details.User guideBucket Moth Trap (mains and inverter) - Instructions Back to Recording Butterflies and Moths Back to Moth Traps

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Citizen Science - Montana Moth Project - Northern Rockies Research & Educational Services

Citizen Science “Moths have great potential in citizen science. Moth-watching, and especially moth photography, are taking off as a new great craze after bird, butterfly, and dragonfly watching. Get a moth trap and help discover your local biodiversity thus providing a baseline for monitoring changes in the environment.” – David Lees & Alberto Zilli, Moths: … Citizen Science Read More »

Montana Moth Project - Northern Rockies Research & Educational Services

Here's a great build guide showing how to waterproof the light.

This is where I got the idea for the lampshade ring from... it's genius!