I am leading a “mothing” program this Saturday April 26th where I’ll hang up a white sheet and UV lights. I’ve done this a few times before in my life in different places but this is my first time doing it as a program. For some background info, the program will be 8:30-9:30pm in a (maybe 100-acre) wooded park in suburban metro Washington DC area. I have a white sheet and some UV lights that the nature center had. This Saturday is supposed to have light rain during much of the day and tapering off at night. The program is timed during a new moon in our area.
Today I did a test run from about 8:30-8:45 in the location I’m planning to do the program. I put out the sheet and lights I will use and got mostly flies and a few beetles, and one or two moths. (This is nothing against flies or beetles, I love them as much as any moth or other creature!) However now I’m a bit worried that I won’t get many actual moths, as I branded it somewhat as a “moth-ing” program (I said we’ll see moths and other insects).
For those who have more experience, would yall expect more moths to arrive a bit later in the window until 9:30pm? I know different species can fly at different times of night but we’re not going very late. I have some strong white LED grow lights I could bring and set up along side the UV lights, if that would be likely to attract more moths. (I did notice a neat moth by the light on the outside of the building at this time.) I could also do two separate stations, one with white light, one with UV. Has anyone tried putting out old mashed up bananas or anything to attract moths and other interesting insects? Would it help to put the lights out earlier? It starts getting dark around 8:00pm here. Or is it just early in the season and not many moths are active at this time of year? I’m trying to see if there are any ways I could attract a greater diversity of insects, but I’m also trying to get an idea of what my expectations should be so I can pass that on to program participants.
My limited experience is that the number of moths you see will depend a great deal on the temperature when it gets fully dark. The forecast for DC on Saturday evening is about 60F, which is a cool for many moths. That combined with the wet weather could make moths hard to find. Others here are more experienced moth-lighters (and know moths around DC) and can probably give you more information. One approach would be to look up the most prolific observers of moths in the DC area… and maybe contact someone like https://www.inaturalist.org/people/stazandgazer for advice.
Would it be worth adding some lures to the light attractions? I’m sure there are recipes online for the various treacle mixes that lepidopterists used before light traps were invented.
Light rain shouldn’t be an issue. Moths like cloudy nights better than clear ones, and drizzly nights have been some of my best moth hunting. Your biggest problem will be that the event is ending too early. 9:30 is very early to end a mothing session. The vast, vast majority of moths come later. There are plenty of species flying in Ohio right now, and I would assume DC as well, but most don’t show up until very late at night. Regarding your UV lights, the fluorescent tube kind work much better than LED. LED will still bring some moths but not as many. Combining UV with white light helps in my experience, but I wouldn’t have a separate station for the white lights. I would combine them. I use moth bait occasionally, usually early in the spring, but have found the results to be somewhat disappointing. Lights are way more effective than bait.
Thanks so much for the thoughts! Temperature definitely was not top of mind since it’s been generally nice here lately so hadn’t considered that it might be too cool that exact day for some moths. I guess nothing I can do but good to know! Interestingly another commenter said that mist or drizzle can actually be good for moths, which I read somewhere before and was surprised about.
Thanks for the info, that is super helpful! I will combine all the lights I can, not be too optimistic for moths given the time, and let people know that more moths fly later in the night. So would something around midnight or later be good for seeing the most moths specifically or general diversity of insects? Do you think setting the lights up as early as possible will make a difference?
I think it couldn’t hurt to try but given what the other comment said about the baits not being very effective, and the fact that I don’t have a ton of time left to prep, I think I will not worry about baits this time. But thank you, definitely would be cool to try another time!
I don’t think setting the lights up earlier would help. Not while there is still any daylight left. Running the event later than 9:30 PM would definitely help, if the park’s rules and logistics permit it. Moths will come and go all night. Exact timing can kind of depend on the weather conditions, but generally the later the better, unless temperatures really plummet sharply overnight and it gets too cold (below 50 degrees). A lot of the big silk moths fly at 2:00 or 3:00 AM!
WRT the lateness of many moths, if you could leave the sheet running overnight or mostly overnight, would they remain until the morning? I appreciate this is less useful for the OP, but it is something I have wondered, as an early sleeper.
Yes, a bunch of them do remain on the sheet until morning, but there is a big caveat here. If you leave the light on overnight, you MUST get up early before any daylight to check the sheet. At first light, one of two things will happen. Either the moths will fly away, or the birds will eat any that remain. Note I’m talking about first light not sunrise. If sunrise is 6:00am, first light is roughly 5:30am, and you need to attend to all the moths before then or they will be bird food.
There seems to be two aspects for the temperature: the temperature itself and history. Low temperature after higher one is the worst combination.
The nights with light drizzle tend to be warm. That might or might not explain why they are good. I also have a feeling that those are the nights when you can get females of Notodontidae or Lasiocampidae. Another aspect to think is light conditions: Full moon and clear sky is a bad combination for light traps. I would assume city lights could have similar effect. Not much you can do about that, though.
My experience with timing is that I might see some Geometrids earlier, but Noctuidae start only at 11pm in the summer and the real flight starts at midnight. However, that is in Finland, where the summer nights don’t get completely dark … AT ALL. It might not be that bad yet or where you are.
As others mentioned 9:30 is just when the fun would start, on a good night. Ideally midnight would be the time to end. I have had some decent amounts showing up when I got out around 10 if it is a really warm day. Best of luck with it though.
I don’t have much tips on mothing, but here are a few:
.Try to set up some sort of light source. You might not get any moths, but probably a few beetles or bugs.
Try to get a bit further away from other light sources eg. Street lamps.
.Try Not to expect a lot of critters. Nature spotting is a game of luck, and there’s no telling what will happen.
Of course, you could just watch local street lamps or lights on walls where moths could perch, which is pretty easy. I’d recommend just doing a few moth-screens or just generally learn about them on the field. You’ll get the hang of it eventually, the more you try.