[TN-Butterflies] Balance of Nature

  • From: Julius Basham <juliusbasham@xxxxxxxxx>
  • To: TN Butterflies <TN-Butterflies@xxxxxxxxxxxxx>
  • Date: Tue, 22 Jun 2010 14:49:29 -0400

As each new Butterfly season unfolds, I find myself marveling at the constantly changing set of variables that cause the rises and falls in general butterfly populations and individual species numbers.  In the several years now that I have been butterflying, I have seen no two years alike or even vaguely similar.
The timing sequences for the emergence of hostplants and the larvae that munch on them, seem to be so delicate, that the slightest weather event has a major impact on what we will see weeks later.  At any given location, the amount of sunshine, rainfall, hail, wind, humidity, etc. determines the annual viability of each fragile little creature.
SE Tennessee is very lush this year and in the last few weeks we have experienced almost daily, wild and raucous, thunderstorms passing through, leaving us with quite a few worn and tattered individuals.
How good of a year the predators are having, is another element that determines butterfly population.  This year seems to be especially good for Dragonflies  and Robberflies.  Their numbers seem to be up 2x-5x more than I have seen in years past.
While on an outing on Sunday, I was photographing this blissful little CW couple.



When all of a sudden this giant dragonslayer (Dragonhunter) swooped in 3 ft. from my nose, caught the couple and started ripping them to shreds in flight, before landing and finishing the task.  It was gruesome to watch.



The numbers of Dragonflys cruising around in the swamps, that I usually check out this time of year, is absolutely amazing. I don't see how it is possible for a butterfly to survive in a place with so many rapacious creatures searching them out.
There are almost no Skippers to be seen, where there are normally quite a few.  No Leasts. No Cloudeds, No Zabulons. a very few Duns and Glassywings seen hiding in the leaves.  The swamps are usually loaded with Little Woods and Carolina Satyrs, but none this year. Even the Appalachian Browns, that like to hide in the leaves, are drastically reduced this year.

And the Robberflies, my goodness, I had no idea there were so many species.  There are many great websites devoted to the Asilidae family.

Norman Lavers in Arkansas  http://www.normanlavers.net/index.php  Check out the photo of the Robberfly that just caught a Dragonfly, holding onto a leaf with only one leg.  Great Photo!
Giff Beaton in Georgia  http://www.giffbeaton.com/Robber%20Flies.htm
Fritz Gellar  http://www.geller-grimm.de/asilidae.htm

This is a page at BugGuide that will leave your hard drive smoking with too many photos to look at in a month.
http://bugguide.net/index.php?q=search&keys=robber&search=Search

On a normal summer's day outing in years past, you might see 3-5 kinds of Robberflies, but this summer there are 10-15 species seen in a day, with new kinds showing up on every outing. I'm witnessing an average of 4-5 butterfly kills per day by Robberflies. Between the Flycatchers, Bluebirds, Cuckoo's, Dragonflies, Robberflies, etc. It's a wonder that there are any Butterflies left at all this year.

This is a common species the Promachus bastardii, with a white hairy cover on his tail. Nice blond beard too.



Then there's this one with a black tipped tail.




This little Golden, Laphria sericea, seems to prefer the swamp environment.



Two Saturdays ago on Raccoon Mountain near Chattanooga. I was observing several gorgeous little Coral Hairstreaks nectaring on an Orange Milkweed.



When this big Military Machine Robberfly came in and snatched one up.



Its just butterfly carnage out there this year.
Here's a little Coral Hairstreak paying his respects to his fallen comrade (upper left on the cross)



I'd be interested to hear if any of you are seeing the same disproportionate balance of butterflies to predators this year in your areas of Tennessee.

Julius Basham















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