Updated: Oct 26, 2020
Wikipedia says, "Birdwatching, or birding, is a form of wildlife observation in which the observation of birds is a recreational activity or citizen science." Exchange "moth" for "bird" and the definition works just as well. "Mothing" is an easy activity you can do in your own yard with little or no extra equipment.
Moths are in the same order as butterflies: Lepidoptera. Butterflies get all the attention because they are pretty and active during the day. While many moths are less colorful, there is a lot of beauty and color if you look closely. There are far more moth species than butterflies and they are important pollinators, but they are less well documented. Citizen science can add to the data about them. A few of the moths I have posted to iNaturalist have been identified as recently discovered, as yet undescribed, and unnamed species. Those are always fun finds!
National Moth Week is an annual event that, this year, occurs July 18-24. "National Moth Week celebrates the beauty, life cycles, and habitats of moths." Everyone is encouraged to be a citizen scientist during that week. Your observations can be recorded on iNaturalist or several other platforms and this counts as volunteer service.
Mothing usually involves attracting moths with light. Often UV blacklights. I like to get the lights turned on by sunset to increase the chances of good bugs showing up, and because it’s easier to set up while you still have daylight. The action starts off slow, but you should have good results in about two hours. Some of the bigger and exciting moths seem to wait till around midnight. In one of my less productive windy nights recently, I counted about 20 moths at 2 hours and at least another 10 an hour later. Even on a slow night, there will be other insects to observe. A couple nights before, I had so many moths I didn't even consider counting them.
Since the rains started again, moth numbers and variety that I attracted this June really increased. Then things slowed down again, maybe because it has been so windy in the last several days. Temperature, weather, wind, and location will all make a difference. If your yard attracts a lot of butterflies during the day, that is a good sign you will have a good mothing experience. If you live out in the country or get a chance to go mothing at a park, you will probably attract more than I find in my city yard.
Sometimes I run the lights until 2 or 3 a.m. Of course, I don't stay out there all that time. I usually go out two or three times over the course of the night. If you are not a night owl, another solution is to get up early before sunrise.
Moths and other insects are attracted to most light sources except for yellow bug lamps or white LED bulbs. Those don't emit much light in the spectrum insects like. Regular incandescent or halogen white lights can be used if you want to try out mothing without purchasing anything new. Maybe your porch lights already attract insects. For better results though, you will want a blacklight (ultraviolet or "UV") bulb.
My favorite inexpensive UV bulb has been the 9-watt LED A19 by Feit-Electric, often available in store at Home Depot pre-pandemic (possibly not anymore). I like it because it is durable, works well, and doesn't cost much.
HEB and now Home Depot carry a 7-watt Feit-Electric LED bulb for half the price with a glass bulb. Even though the wattage is lower, I found these attract more moths.
Walmart has a very inexpensive Great Value 7-Watt LED Black Light. I don't recommend it. The above products put out a lot more UV light.
You may also find a 75-watt incandescent blacklight bulb for around $3. Don't buy this one. They aren't as effective and get really hot. I would rather a white 75-watt bulb over this.
My fluorescent and compact fluorescent (CFL) UV bulbs do seem a bit more popular with moths than my LED bulbs, but those aren't as easily found locally. Since I haven't bought a new one in many years, I don't have a recommendation for these. A pair of BlueX CFL UV bulbs were recently recommended in a Mothing group. I don't usually bring my fluorescent bulbs when I moth away from home since I worry about breaking them.
A clamp shop light fixture is an inexpensive and convenient way to position your light where you need it. Hang or clamp on a tree, lawn chair, or other surface. I usually remove the reflector so the light shines out in all directions. Plus, they store better without the reflector.
Once you have the light, you need a white sheet or other surface. The light is what the moths are attracted, the actual surface is less important. I have read suggestions of using a cotton sheet. The ones I have are 60% cotton. You will need a way to secure it such as clamps, clothespins, or even rocks. You don't want your sheet flapping in the wind or moths won't stay long.
I try to place the sheet where it is visible from the sky so more insects can see it. It doesn't have to be completely out in the open, but under dense tree cover or too far under the porch may not be as effective. At least that is my experience when setting up in an urban environment.
When away from home, I put the sheet on whatever is convenient: fence, picnic table, bench, or clothesline. I have also used the metal siding on a garage, with no sheet.
You will get less visitors to the sheet on windy nights, and the moving sheet will make it a real challenge to focus on your subjects. In this instance, a table set up works better. If you're stuck with a suspended sheet on a windy night, get it as tight as you can make it.
Some moths also come to butterfly bait. I have seen a bunch of Black Witches on the bait logs at the National Butterfly Center in November. See their website for the recipe.
Examples of Moth Sheet Setups
My home setup is always evolving and depends on the weather. On the left side in the photo, a sheet is stretched horizontally over two sawhorses with a fluorescent UV light. I would move it under the porch if it might rain. The setup on the right has a sheet suspended vertically from the porch roof and anchored at the bottom, illuminated by several LED blacklights in clamp work light fixtures. You don't need a lot of lights like I have, but since I have them, I use them. One is enough to get started.
The image below shows a lepidopterist's setup, consisting of a collapsible frame and custom fitted sheet. They use a single battery powered fluorescent mothing light from BioQuip. Most of the lights you see here are flashlights.
Here are a couple of setups at Oleander Acres in Mission on one of our mothing get-togethers. On the left is friend of the chapter, Cat Taylor's setup: a sheet stretched around a rectangular PVC frame with several UV bulbs inside. Maybe in a future blog post you can follow along as I make my own. The setup on the right is a sheet clamped to the trellis at the entrance to the garden.
And last, a setup by Anita Westervelt who encouraged me to finish this blog post. I sent her some draft versions I have been working on (for years) to help get her started with mothing for the 2020 City Nature Challenge. Due to the COVID-19 pandemic, she used what was on hand. An aluminum work light was clamped to a camera tripod at one end, and another was clamped to a ladder at the other end.
To take photos, or even really see what shows up on the sheet, you will need a flashlight. Against the glowing blue sheet, moths and insects will be a dark silhouette. The camera's focusing system can't "see" well enough in that low light to focus. With a flashlight or headlamp, you will still need to use the camera flash. A flashlight usually won't provide enough light to get a sharp photo, and the blacklight glow may confuse your camera.
Different moths and insects are attracted to different wavelengths of light. The inexpensive bulbs I use don't usually specify their wavelength since they are intended as party lighting for making posters and clothing look groovy. Anita helped me with that sentence, I doubt I have ever used that word before, but I think it fits.
If you get really into mothing, you can purchase some high-quality equipment and materials meant specifically for mothing. Mercury vapor lights (old-fashioned street lights) are very bright and put out a wide spectrum of light that moths love. UV bulbs from BioQuip, designed for mothing, put out more of the UV spectrum than the bulbs discussed earlier.
For your sheet, you can also order rip-stop material which has little squares that can be used to estimate the size of your subjects in photos, which can be helpful in identification.
One piece of equipment you probably don't want is a white shirt unless you enjoy moths swarming and landing on you.
I am not able to identify very many moth species but I enjoy them and I can talk about them being nocturnal, being pollinators, being food for bats and birds, and being closely related to butterflies. Moth Week is focused on just the moths, but I am interested in all insects. Lacewings, mantids, mantidflies, ladybugs, katydids, flies, ladybugs, June bugs, and many others are regulars at my moth sheet. I want to learn what is in my yard and elsewhere in the RGV. Kids at the events I have volunteered at were interested in all the types of insects that showed up too. At a recent moth setup, we had a dragonfly visit; they are not nocturnal, so it was very confused by the UV lights. We were able to discuss how dragonflies have great daytime vision, but apparently it's not so good at night. One of the questions I often get is why are moths and other insects attracted to UV light? We don't really know. Some of the theories include moon navigation or UV reflecting off of flowers.
UV Bulb (LED or fluorescent)
An extension cord
Clamps, clothespins, or other implements to secure a sheet
Something to support the light fixture (tripod, ladder, chair, etc.)
Possibly sawhorses or a table
Flashlight so you and your camera can see the moths to focus