Thursday, March 15, 2012

Monarch moment, part 2

The natural result of this...
From a Centerpointe Communicator post of about a month ago.  Except I think I initially called the sex wrong on this one... upon closer inspection it appears to have been a female because it lacks the characteristic small black patch of pheromonal scales on the hind wings that males have
...surprisingly, turns out to be this:
Monarch caterpillars.  Lots of 'em.
Before departing our humble abode, one or more of last month's monarch visitors laid eggs.  This is one of the reasons why I like to have abundant landscaping in my yard: it's not just nice to look at in a passive sense - all kinds of interesting stuff happens out there.  It's an entire story unfolding on a daily basis in a ridiculously-small suburban back yard and, of one gets off one's duff and actively starts looking around, a lot of that unfolding story becomes evident, and there's plenty of learning opportunity in it.  I didn't know that monarchs actually bred and reproduced this far south.  I thought they proceeded farther north on their annual migrations before doing that. 

I seemed to have had far more caterpillars than milkweed available to feed them, because they stripped the plant bare.  That raised the obvious question: should I have culled the herd, leaving more milkweed available to a smaller number of individuals, or should I have let nature take its course??  Knowing very little about the life cycle of monarchs, I decided on the latter.
As the milkweed plants were getting stripped bare (they'll grow back from the roots), and the caterpillars began abandoning the urn of milkweed, presumably looking for more of it elsewhere.
"Is there any good way down from this thing?!?!"
This guy got one of the last available leaves.
And this guy decided to eat his last leaf upside down.
My milkweed recently went to seed, so I plan to harvest these and try to get more plants started, to be ready for next year's migration.  Monarchs are the only species of butterfly to engage in long-distance, round-trip migration, as many bird species do.  Except the monarch's lifespan is not long enough for any single individual to make the entire trip.  It takes three or four generations to complete the cycle.  They apparently use the earth's magnetic field and the sun to navigate in ways that nobody really understands, and the instinct to migrate is genetically-encoded
Notice how this guy had a larger yellow head and some larger sucker feet than the other individuals.  I don't know why this is.  Was he a different sub-species, did these differences represent the beginning stages of metamorphosis, or did this represent something else entirely? 
As of this morning, all of the caterpillars have vacated the now-stripped milkweed and have gone about their mysterious ways in doing whatever comes next for them.  I don't know if any of them got enough nutrition to make it through their chrysalis stage.  I was kinda hoping to see a few cocoons hanging around our yard because they're really neat...
They start out looking like this...
...and then toward the end of the metamorphosis, you start seeing the butterfly forming within.
So perhaps if I get lucky, I'll find a coccoon or two somewhere in our yard in the next week or two (how far can caterpillars travel from a host plant before they have to hunker down for their change of life??).  And within a few more months, hopefully I'll have more milkweed.

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