Sunday, August 28, 2011

Night of the Polyphemus Moths

When I was growing up in the 1950s, we used to find lots of the Giant Silk Moths (Saturniidae), such as Cecropia, Luna, Polyphemus, Ailanthus, etc. -- even in the city, where their caterpillars fed on leaves of street trees, and the moths came fluttering to the windows.    But in recent years their populations have declined, due to loss of habitat, insecticides and, some scientist believe, night flight confusion caused by light pollution.  When we moved to the country in 1988, I was looking forward to maybe seeing them again, but even here, sightings are few and far between.

So you can imagine my delight when, in the spring of 2005,  I found a Polyphemus cocoon under a birch tree in our yard.   I put the cocoon in a bed of dead leaves (simulating its natural environment) in an empty fish tank with a screen top, and awaited the emergence of the moth.

Female Polyphemus Moth
(Photo courtesy of Wikimedia Commons)
On June 30, 2005 she emerged -- but the weather was so cold and windy (with 50 mph winds) that I could not release her.  The storm continued thru Saturday night, so I attempted to release her on Sunday at dusk, which was around 10:00 PM here in the midsummer northland.  I took the top off the cage, put it in the upstairs window with the screen open, and expected her to sail off into the woods the way butterflies do when I release them in the daytime.  Only the moth would not fly away.

What I did not know is that a female Polyphemus does not fly until after she mates.  So she just sat there in the open cage, giving off her pheromone mating call -- and wow, did it work!  Around midnight I went upstairs to see if she was gone, and the room was full of polyphemus moths!  The female had flown, all right, leaving behind six suitors who were still sitting in her cage and on the walls, getting high, I suppose, on the lingering smell of female moth.

That was more of these big moths than I had seen in many years.   I was surprised but also pleased, because it indicated the local population was bigger than I had thought.  I later read that a male can detect a female from a mile away -- or even more.  Whether or not there were other females in the same radius sending out their mating scent to other males, I do not know.  But six males on my land in one night was certainly beautiful!  I carefully picked up each moth and put them out the window, watching them fly off into the night.   Two years later, in May 2007, I found an empty Polyphemus cocoon under the same tree.  I like to think it was descended from  the Night of the Polyphemus Moths.

In more recent years, I have found empty cocoons of Cecropias and an occasional Polyphemus or Luna, but have not seen many of the adult moths.  Still, it's nice to know they are still out there.


Shunraya said...

עַד-שֶׁהַמֶּלֶךְ בִּמְסִבּוֹ נִרְדִּי נָתַן רֵיחוֹ.

Seems your male moths have their own version of Shir HaShirim!

Yonassan Gershom said...

LOL, Shuraya! It was definitely a mating call :) Imagery changes with the centuries (I doubt few women today would be impressed with being compared to a flock of sheep flowing down the hills of Ein Gedi!) but the springtime urge remains the same.

Tor Falcon said...

How lovely.