A moth’er’s materials

I don’t think I’ve ever gone into any detail regarding the equipment I use for mothing. I had a comment on yesterday’s post asking for more information about it, so I though I would follow up and make that the subject of today’s post. That way, interested readers can gather their own mothing equipment if they wanted, and it would be with lots of time before the spring mothing period begins!

In reality, you don’t really need to have special equipment in order to enjoy moths. Especially in the country, but also in urban areas, you can go outside and check your porch light or the windowsills around windows where you have your lights on. Moths and other crazy creatures will be drawn in to just about any artificial light source.

If your curiosity has got the better of you, however, you can up the ante by setting up a white sheet. These will also work with just a simple incandescent shone against them, but what really brings in the bugs is to use a lightbulb that projects partially in the UV spectrum, like a blacklight. Make sure you’re using a standard cotton sheet – synthetic materials tend not to glow under blacklight the same way.

It’s not clear why moths, beetles and other bugs are attracted to UV light; it might have something to do with the wavelengths mimicking the pheromones of other individuals in the way they hit the bug’s antennae. Another hypothesis as to why moths come to light is that they navigate using the moon, and since the moon is simply shining with reflected sunlight, it’s possible the bulbs mimic the UV in the moon/sunlight. Regardless of the reason that it does, UV bulbs really work.

I have three types of mothing equipment: sheets, trap and “goop”. This is my sheet equipment. It consists of a white sheet, a spring-clamp light bracket and UV bulb, and a tripod (not pictured). I hang a sheet from a clothesline or a rope strung between a couple of trees, clamp the light bracket with bulb onto the tripod, and set it up in front. You’ll have more success if at least one side of the sheet faces an open area, since the light will broadcast farther that way and draw moths in from further away.

The two bulbs I have shown here are a blacklight and a mercury vapour. The blacklight is easily available (as is the spring-clamp bracket) from any Home Depot or Canadian Tire or similar stores that sell bulbs. I’ve found the compact fluorescents to be brighter than the incandescent versions. All blacklights have the finicky requirement of being held upright – I found out the hard way that if you hang a blacklight upside down it burns out within a few minutes. The exception to this is the tube-style, which you can get at party stores and the like.

The mercury vapour is less easy to come by, and you may end up having to go to a specialty lighting store to find it. I ordered mine off eBay. Unfortunately, when they arrived I discovered they had mogul bases – the old-style, inch-and-a-half diameter size – which wouldn’t fit into the sockets I had. So I then had to buy a converter off eBay (also not available in Home Depot) to fit my mogul bulb into my normal socket. Works like a charm, but wasn’t so cheap.

The upside to mercury vapour is that it’s really, really bright and so broadcasts a much greater distance than a blacklight. The light is also stronger, and so you’ll end up with more moths coming to your light than you would with simply a blacklight. The downside is that it’s more expensive, and it burns hotter than a blacklight. Also, because it’s so bright and it’s casting UV rays, you’re advised not to look directly at it. When you buy your first mercury vapour bulb, you know you’ve gone hardcore. It’s like buying yourself your first several-hundred-dollar pair of binoculars.

The other way you know you’ve gone hardcore is that you build yourself a moth trap. Moth traps are delightfully easy to make for the reward they offer. They have the advantage of allowing you to run a light all night, without having to actually be present to check what’s come in to the sheet. You can run them rain or (moon)shine, with the proper protection. And, they keep all your moths contained until you get up in the morning and start going through them over your cup of coffee.

The general principal of a trap is that the moths come in to the light, and then during all their frantic fluttering around (in that way moths have around lights) they end up falling down the funnel. Once into the trap, it’s very difficult for them to find their way back out. Then climb onto some of the stuff you’ve tucked inside and wait for you to come release them the next morning. Any set of equipment that accomplishes this goal will work, and there are different styles to approach it. My trap is a large rubbermaid storage tub (shown below), while TheMothMan‘s (pictured above) is a garbage can with a plastic sheet over top (or at least it was, I think he’s switched out his arrangement recently).

Of course, when using a trap there are obvious ethics involved. Make sure that you don’t keep your moths in the trap longer than necessary. If you want to hold some for photographing or showing off to a friend, that’s fine, but make sure you put them in a container and place them in the fridge. Pill bottles are a great size for this (there are some shown in the photo of the folded sheet above), and you can ask your local pharmacist if they may have some you could have. Alternatively, they can be ordered from specialty shops online, but basically any smallish container works fine – clear ones are best since you can see what’s inside. The cool temperature of the fridge will keep moths calm and lower their metabolism, putting them into a sort of torpid state. This same applies to any moth you want to keep from your sheet setup. Don’t place your trap in a location where the morning sun is likely to rise and heat it up before you can come out to rescue the moths (or if you have no choice, then make sure you’re up before the sun is very high).

Also, protect the trap from rain as best as you can. This can be done by placing a glass bowl inverted overtop of the bulb. You don’t want the rain hitting your bulbs, and it’s better not to have it draining into the trap, either, if you can (although if your trap is made to drain properly then it’s not the end of the world; if it’s not, however, you can end up with several inches of water and dozens of dead moths floating on top). Moths will still fly in the rain, so just because it’s rainy won’t mean there’s no moths. If you don’t have a glass bowl, you could also string up a tarp or put the trap under an overhang where it won’t get rained on. When you’re releasing the moths from the trap, make sure you release them into long grass or thick shrubs, so that they have protection from predators. Also, try not to dump a hundred moths all in one spot if you can – as soon as a predator such as a bird stumbles onto the smorgasbord, that’s it for the bunch. You can release them during the day, just make sure it’s into appropriate cover. If you have no appropriate cover, try to release them at night.

As for the details of trap construction… Choose whatever container you prefer. It needs to be reasonably deep, but if you don’t like leaning into a garbage can then it’s okay to go for something shallower. The main concern is that it will fit your funnel. The funnel is a large-sized plastic funnel the likes of which you can get from Home Depot or Canadian Tire or other hardware/auto stores. This one is 10″ across, I believe. The bottom part of the funnel has been cut off, resulting in a 4″ opening. Attached to the bottom is a 4″ plastic plant pot with its bottom cut off, extending the funnel but still leaving the mouth wide enough to accommodate large moths.

Inside the funnel is the trickiest part of the trap. You’ll need to get a light socket with a cord (the spring-clamp bracket usually has a screw that will release the socket from the clamp), or otherwise make your own. The socket needs to be suspended in the middle of the funnel, so that the base is about halfway down. In my trap this was done by cutting some pieces of clear acrylic to the appropriate size/shape and securing them inside the funnel with silicone. You could also use strong wire or some other means. If you use acrylic it can be used as struts to support your glass dome, just make sure that it sticks up high enough to leave a gap for the moths to enter. If you use wire, make sure it’s strong enough to support your dome, and use a dome that’s smaller in diameter than your funnel, or otherwise build additional supports (eg blocks of wood) outside the funnel to support the dome. Now that the hard part is done, measure and cut out a circle from your trap’s lid that you can slide the funnel into.

Inside the trap, you need to make sure there’s something for the moths to cling to. One of the best things is empty egg cartons, or other items that are similarly rough and full of nooks. Moths like to tuck themselves into nooks, like they would hide under a piece of bark, and egg cartons appeal to this. I buy my eggs in plastic cartons, however, so many of my substrate items are actually biodegradable seed-starting trays. When you put them into the trap, stack them around the outside. This leaves room for the funnel, but moths that enter the trap also have the inclination to head for the walls, and putting the substrate against the walls will mean they’re more likely to stay in the trap.

The third and final tool moth’ers use for attracting moths is a syrupy “goop” that is spread on trees or logs to draw in nectar-feeders that may have limited interest in the light (not all species of moths are attracted to light). Most moths don’t eat as adults, but there are a few that sup on flower nectar or tree sap, and this is the group that the goop will appeal to. To make it, throw an overripe banana, a dollop of molasses, a scoop of brown sugar, and a few chugs of cheap beer into a blender and mix it all together. If you get the impression that the measurements don’t need to be precise, you’re correct. Anything sweet and sugary will appeal to them, so if you’re missing an ingredient that’s okay too, although the beer really is a helpful addition.

Take this concoction and, using a wide brush like you might paint your house with, paint it onto the trunks of a few trees or logs. It may take the moths a little while to find it, so it’s good to put it out early in the evening. Note that it has the potential to stain, so don’t put it onto your house siding or anything you might be worried about leaving a mark. Goop is most effective on cooler nights, in early spring or late fall, but can be used at any time of the year.

Pretty much any evening where the temperature is up around 10 oC (50 oF) and above there’s the potential for decent mothing, although naturally cooler evenings will be slower than warmer evenings within the same time period, and cooler months will garner fewer moths than warmer months. The height of mothing is really June and July – that’s when the most colourful moths are out and about, and the greatest diversity – but any warm night is good mothing.

So there you are! All set to get going watching moths in your own backyard. Us northern folks still have another couple of months before the temperatures are warm enough to get started, but I suspect folks down in the balmy south could be mothing year round. A good evening of mothing can be a fun experience, particuarly as a social event – invite a few friends over, string some sheets up, crack open a couple beers (or glasses of wine), and laugh and have a good time. And let me know what you get!