Thursday, October 27, 2011

Linden Looper Moth

Linden Looper - Erannis tilliaria
Also known as the Winter Moth.  I've been seeing them here and there since some time in September.  The caterpillars are a type of inchworm (family Geometridae).  The Linden Looper is well adapted to the cold, which hasn't mattered much this fall given the warm weather.

I've found a lot of Linden Looper Mothsthis fall perched on the side of the garage at Westwood Hills Nature Center.  The males are attracted to the lights that stay on all night on the garage.  They don't seem to be doing much; I've found a number of them in the exact same spot for days; I haven't counted how many days in a row, more than three I suppose, usually by that time I can't resist the urge to poke at one to see if it's still alive.  They always are and fly away.  My question from this observation is why don't they move at all, apparently not even at night since they'll stay in the exact same spot (until I get too curious).  If they are in one spot for days, they aren't feeding or mating, the only two things that moths really do (as far as I know).

The female Linden Looper Moths are flightless, which is the case for a number of cold weather Geometrids.  I wonder why this is, and if flightless females are found in other groups of moths in other seasons.  I'm only aware of flightless females in the Geometridae (but I'm by know means a moth expert).  From an evolutionary perspective you would wonder what the advantage of this trait is, and it how might be related to the cold (there are Geometrid moths with flightless females active in the spring and fall).  I found an article that may provide some answers entitled "Evolutionary Adaptation of Contractile Performance in Muscle of Ectothermic Winter-Flying Moths" by James H. Marden in The Journal of Experimental Biology.  I'll let you know what I find out.

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