Mallee Looper moths (*Arhodia* spp.) attracted to a moth sheet. Photo: Mark Hura.

Why would you want to trap moths?

My uncle tells me gleefully about his trap to kill pantry moths. That’s not it!

I trap moths because it is fascinating to see what sorts of moths (and other insects) are flying around at night, normally unseen by us. But I don’t want to kill things, just so I can look at them. My moth traps are no kill. (More about that here).

So how do you trap moths you may ask. Read on for moth sheets and moth traps …

What is a moth sheet?

As in the photographs above, it is simply a white sheet, strung between two trees, with a moth-attracting light nearby. Moths are lured to the light and rest on the sheet making photography pretty easy. But it’s a night-time activity. The really keen folk might check their moth sheet all through the night… Did I mention I’m a morning person? If the moths haven’t arrived by 10pm, I’m off to bed.

I have had some excellent evenings with a moth sheet though. Like when Roger Standen and I found a Hawk Moth that was a new species for Victoria and a significant southern range expansion (Coenotes eremophilae). The best conditions for a moth sheet is around the new moon, when it is nice and dark. A calm, humid and warm night helps also.

How to make your own light sheet to attract moths

It’s deceptively simple. Hang a white sheet from a rope and place a moth-attracting light nearby. Secure the bottom of the sheet so it doesn’t flap about. We wind the bottom of the sheet around a length of PVC pipe and then secure the pipe on the ground with tent pegs.

For the light and power source I use:

Light - A 240V replacement light for bug zappers 50W Gecko brand (about $30). It is fitted into an Arlec 60W handheld work light housing with a 5m lead ($15).
Power source - I plug it into a power point with an extension lead or use a battery with inverter like the Powertech 155W power station ($220).

Desert Hawk moth (*Coenotes eremophilae).* The first record for Victoria was on Raakajilm and a significant range expansion.

What is a moth trap?

I don’t like staying up late at night so I was very excited to discover the set-and-forget moth trap.

There are many designs but the one I have chosen is a bucket with a funnel in the lid. The moth-attracting light is suspended above the funnel and is surrounded by four transparent vanes. The moth flies towards the light, hits the vanes and is directed down through the funnel. Moths accumulate in the bucket overnight and I check the catch early in the morning. No sleep lost!

My DIY moth trap, coming in around $100 including the power source.

Make your own moth funnel trap!

To make your own funnel moth trap get yourself:

20L bucket ($15)
Giant big mouth funnel ($12).
Insect netting ($8 for 120x210cm) - this is enough for two traps
4mm clear twin wall polycarbonate sheet ($16 for a1200x600mm handisheet from Bunnings). You can cut vanes for two traps from one sheet.
A 5W USB UV tubelight ($22)
A 20,000mAh power bank ($40)

Total spend = $113

To “build” it:

Cut the netting into a piece 130 cm x 60 cm. The netting is draped inside the bucket to give the moths somewhere to land. You can sew it into a bag, or leave it flat.
Cut the long bit off the funnel, leaving about 1cm. The funnel will fit neatly into the bucket.
Cut the polycarbonate sheet into two pieces 29 cm x 42 cm (see the pattern here). We used a circular saw (with full face mask protection for plastic shards).
Cut a slit in each piece of polycarbonate (again, check the pattern). For piece A, cut a slot 22 cm long from the square end. For piece B, cu a 19.5cm slot from the pointed end. The two pieces slot together to make four vanes that sit inside the funnel.
That’s all the building!

Parts of the DIY moth trap: 20L bucket, cut-off funnel, transparent vanes, 5W LED UV light, 20,000 mAh power bank.

How to use the moth trap

Find a spot in the bush or your garden to hang the bucket from a tree branch, or you can leave it on the ground.
There are two options to drape the netting inside the bucket:

If you are trapping in cool weather - You can simply fold the netting in half and drape it inside the bucket. Make sure the edges inside the bucket overlap by about 5cm so the moths don’t sneak out the sides. Secure the netting at the top of the bucket with a really big elastic band. This is the easiest method if you are going to photograph the moths straight away. You can easily remove the elastic band and then lift the netting out of the bucket and spread it out flat to see your moths.
If you are trapping when the nights are >15oC overnight - You will likely need to subdue your moths in the fridge so you can observe them without them immediately flying away. You’ll need to sew up the sides of the netting to make a bag that goes inside the bucket. In the morning you can remove the bag, place it in the fridge for an hour or two, then open the bag so you can see and photograph the moths. The cold makes them less active so they are happier to pose for photographs. My family loves opening the fridge to find it full of moths.

Once you have arranged the netting inside the bucket, place the funnel in and then sit the vanes on top.
Plug the UV tube light into the powerbank and place the powerbank inside the bucket under the netting (this helps weigh the bucket down).
Hang your light over the vanes, just above the funnel mouth.
You can put the bucket lid on to protect the light from rain showers, and tuck the powerbank into a plastic bag inside the bucket. But it is best not to set it up if lots of rain or wind is forecast.
That’s it! Turn it on in the evening. Go to bed and return first thing in the morning to reveal your moth bounty!
In the photos below, the buckets are sitting in water trays (great idea, Phil and Judy!). This helps to keep ants out. They love to attack the trapped moths. You can use a weight to hold the lid on, or small octopus straps.

Have fun moth trapping! Look at these beauties you might see!

White-spotted Owl Moth

Striped Hawk Moth

Southern Moon Moth

Caution

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Caution 〰️

The UV lights will attract moths. Sometimes a lot of moths. Occasionally they might choose to explore your ear holes. This is not pleasant. Please wear ear plugs or a beanie so the moths can’t get in.

This project of the Regional Drought Resilience Planning program is jointly funded through the Australian Government’s Future Drought Fund, the Victoria Government and the Natural Resources Conservation Trust.

No kill moth traps

Sometimes, researchers use a kill fluid like Tetrachloroethylene to kill all the moths and other insects that enter the trap. This keeps the insects in good condition for research and identification because they don’t fly around battering themselves to death, or get eaten by beetles also captured in the trap. However it was super important to me that I not kill everything indiscriminately in the course of my Mallee Looper research. So the moth trap I used had to be no kill.

How to stop the moths battering themselves inside the trap overnight?

I used a large 20L bucket and lined the inside with a mesh bag. This gives the trapped moths plenty of space to hang about without bumping into each other and panicking. I found as long as they aren’t touching each other, they rest calmly in the trap. And in case you’re wondering, you can fit at least 370 moths in a 20L bucket, but it gets pretty busy counting them in the morning! There are 130 Mallee Looper (Arhodia sp.) moths in the bucket in the photographs below.

How to stop the beetles feasting on the trapped moths?

I’m not very good at sewing, so when I sewed my first bag I accidentally left a gap in the seam at the bottom. What an amazing invention! I had made a beetle separator!

Inside the mesh bag, moths climb up and rest on the walls of the bucket, whereas beetles climb downwards trying to get out. The hole in the bottom of the bag allowed the beetles to escape the bag and gather in the bottom of the bucket, keeping separate to the moths that stay inside the bag. This minimised any beetle-moth predation.

How to get the moths out of the trap?

The overnight temperature is important. I cleared my traps at first light when it is coolest. If the temperature was below 15oC the moths were very calm and I could simply pick them off the walls.

Temperatures of 16-25oC meant I had to bundle up the bags and put them in the car fridge to cool the moths down. Putting them in the fridge doesn’t kill them, just subdues them. This makes it easier to sort and count your catch. If there were lots of moths, or the morning was warm, I had to process the catch in batches, putting the bags back in the fridge several times when the moths became too active to handle.

If the overnight minimum temperature is forecast to be above 25oC, I try to avoid setting the traps at all unless it is absolutely critical. The moths don’t settle on very warm nights, and it is absolute chaos trying to clear the traps. Even after a period in the fridge, the moths quickly reawaken and start escaping again.

Birds and ants will also eat your moths

If you set your trap in the same location over several nights, the birds and ants will soon be attracted to feast on the moths.

Ants

You can put your bucket in a water dish (thanks Phil and Judy for that great idea). Otherwise you need to move your trap. It is horrible to find a bucket full of ants and many dismembered moths.

Birds

You know the saying about the early bird … well it is difficult to beat the early bird and they often get the moths. I found that shortly after daybreak the birds would move in and pick off moths that were resting on the outside of the bucket. Then they would hang around, waiting for me to open the bucket. As I released the trapped insects, the birds would fly around my head feasting on the insects as I released them. The only solution was to get up earlier. At one site I needed to clear the traps before daybreak, using a headtorch!

It felt unfair on the insects but I did have lots of lovely experiences with hungry birds. Jacky Winters and Willie Wagtails fluttering about my head. A Grey Shrike-Thrush foraging in the leaf litter where I had hidden the beetles I had emptied from the trap. A pair of Sacred Kingfishers taking moths to their tree hollow nest. A Grey Butcherbird feeding his baby. NO! Not the Christmas Beetle! And a particularly tenacious Striped Honeyeater trying to eat the Mallee Looper moths I had collected into tubs for further research. On two occasions my tubs were stolen by Currawongs. I had to chase after them until they dropped them!