just when I thought I was beginning to have mothing licked!

[joniverson]

Second year setting up the 175 W MV bulb and sheet.  Started in late April and with almost constant watching of the system, I have collected more or less twelve Saturniidae.  When the large ones show up has been more haphazard than anything else, but generally I have had better results with no moon, cloudy skies, and warm temperatures although that's not always the case. 

Take the following example.  Two nights ago, it was cloudy, moonless, and with temps of 75 F and 96% humidity.  I've been trying to save a bit on electricity and don't activate the MV light until 9:45 PM most nights.  I turned it on and even within the warm up period, bugs were already swarming.  It's rare for bugs to show up so quickly, so took a guess that it might be a good night for Saturniidae.  Turns out I was right:  I had two Eacles imperialis show up within an hour of one another.  By 3 AM, I called it a night and turned off the light.

Fast forward to last night.  82  F (one of the warmest nights of the year so far) with 70%+ humidity.  Partly cloudy and no moon.  Thought it was going to be a repeat of the couple nights prior, but almost no bugs!  I didn't even get much swarming around the light. 

Everything I've researched suggests the moon, temperature, wind, and humidity and sky conditions all being factors but could there be something else at work?  I mean, both of these nights were almost identical but a totally different amount of bugs. 

Thanks!   

[kevinkk]

Moonless nights are best, I think a lot of times it's simple luck and timing that causes one night to be better than the next,
if you're staying in the same location, keeping track over time would be interesting.
The only competing factors you might encounter would be other nearby lighting, predators exist, but are probably not going to make
a dent in your catch.
There's also just lifecycle to consider, each year is different and things happen each year at slightly varying times.
For my general area, it's been cooler than normal, by quite a bit, so something like that is going to have an effect.
You're running your light at a good enough time, 3 am is late, and most flyers are down by that time.

[exoticimports]

I can't answer your specific question; as suggested there are other factors likely involved- perhaps factors science doesn't yet recognize. Long-term precise record keeping may solve that dilemma.


On another topic, hours of operation:

First, note that many sphingids fly around dusk. S abbotti for example, I find comes only within the first hour of dusk. At the other end of the night, A luna doesn't show up till 1am or so, and later. By limiting your light to "core" hours you are likely eliminating the extremist fliers- including perhaps those more unusual! My MV is on well before dark; the big issue is late-flying hornets which get squished.

Conventional wisdom says "full moon bad" but that is not always the case; perhaps leps are more inclined to fly distances (or whatever) when navigation is easy, and thus more likely to fly far enough to reach your MV. Last month on a full moon night was one of my best nights. Go figure.

On cost: I pay 4.2 cents (not dollars, CENTS) per KwH. Let's round it to five cents per KwH for taxes and ease of math.

That means I can run one 175W MV for 5.7 hours for FIVE CENTS. If I run it eight hours every night for 30 nights it costs $2.10.

Your real costs for electricity is in HVAC and hot water (if electric...if not, it's still a far greater cost than a 175W MV). I figure my 1000W microwave gets an average of 20 minutes usage per day in winter, so costs 30 cents per month to operate- and that's 1000W not 175W!

So really, you're not saving any significant electricity usage (i.e., negligible ecological impact) or money by reducing MV run-time.

Chuck