Traveling the "Snout Route"

I love the sound of that, a “Snout Route”, and last week, as I drove back from the Wildlife Rescue and Rehab facility, that is exactly what I was on, a road that was being shared, with hundreds, maybe thousands of “Snouts”, American snout butterflies  (Libytheana bachmanii) that clearly had all recently emerged from their pupas and were heading in the same southwesterly direction I was.  

Let me not claim credit for knowing a “snout” when I see one. For that matter, I had to find a straight part of this twisty road to hop out of the car and scoop one up, for sadly they weren’t all able to avoid the windshields that were coming at them.  It was a small butterfly about 1 ½” wide and with orange and white spots on its wings.  But the clincher for the ID is the Jimmy Durante size snout, or what entomologists would call its “labial palpi” that extends way out in front of it.  It turns out it is wonderfully camouflaged to look like a dead leaf when hanging upside down from a branch and the snout makes a perfect leaf stem.  I saw one do this in my own yard and would give it an Oscar for its portrayal of a leaf.

And why so many this late in the season?  Well of course, with my lack of real sense of the “seasons” here in Texas, Oct might as well be as good a time as any other.  Although it turns out that what sparks explosions of these small butterflies is a dry period, or drought followed by rain.  The larvae dine on the omnipresent Hackberry tree and yet they really only like new tender leaves.  Who wouldn’t like a tender leaf over a tough one anyways?  So, when rain comes and the leaves begin to put out new growth the females can lay their eggs and in 12-15 short days you have larva that have gone through their whole metamorphosis and are ready to go.  And often, hackberry trees that have been stripped of their leaves as many in my yard seem to be.

Now, I saw a lot of butterflies, but here is the staggering statistic on them. These few thousand, or who knows how many really, were nothing compared to the Snout Explosion of 1921.  Surely you have heard of it.  In late Sept of that year, 25 million snouts per minute passed over a 250-mile area from San Marcos to the Rio Grande, and that rate kept up for 18 days!!!  In the end, they estimated 6 billion butterflies had passed by!  Yikes!  And what led to that incredible number?  Another year of drought, but then the heaviest rain ever recorded fell, 36.4” in 18 hours and we can assume all the plants, including the hackberry trees went berserk putting out new leaves.  And incredibly, there were the snouts ready to “get at it” and commence multiplying. 

But something else was at work here; they do have a predator, a “checks and balances” thing that nature is so good at. There is a wasp, that lays its eggs in the pupa of the snout. However, this particular species of wasp just couldn’t hack the drought.  So when the rains came and the pupa came off the assembly line, as it were, their parasite was nowhere to be found and the end result was 6 billion butterflies!  Isn’t that wild!  And it has been repeated over the years for drought is surely not uncommon here and neither are the much needed rains that finally fall.  I do believe that that 1921 episode still holds some kind of Texas record, and indeed, even though I thought I was being inundated with butterflies swirling around the car, I guess that was nothing. 

And, one week later, I don’t see any, so they obviously were headed somewhere else.  If you live out west, perhaps they were headed to your neighborhood.  They do winter over as adults though, so perhaps our chances of seeing the skies darkened by mass migrations are waning.  There is always next year, and now you will know what you are seeing.  Of course, I am the new one here; you probably already DID know what you were seeing!  Either way, wishing you a trip along a “Snout Route” sometime in your future.