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The Mountain Pine Beetle

As you drive through Rocky Mountain National Park you see a lot of mountainsides (started to type hillsides and corrected myself!) that look like this.

I admit to increasing the color saturation on this photo slightly to bring out what I want you to see, but the large swaths of red-brown trees are obvious regardless. Something is attacking and killing large numbers of lodgepole pines. The culprit is the mountain pine beetle, Dendroctonus ponderosae.

The dead and dying trees are everywhere you turn.

Pine beetles are native to North America, but droughts and warm winters (likely due to global warming) have led to an unprecedented explosion in their numbers. They infest a pine tree by laying their eggs under its bark, which introduces a fungus into the tree that blocks water and nutrient transport as well as the flow of the sticky pitch, with which the tree might otherwise defend itself. (This is actually similar to how the invasive ambrosia beetle, which I’ve written about previously, attacks bay trees.) Apparently this leads to characteristic blobs of pitch forming on the surface of the bark, and if I’d known that I’m sure I could have found examples to photograph but I didn’t know what I was looking for while I was there.

One of the more effective management techniques is to remove affected trees before the beetles can spread, and we saw some places in the national park where tree removal had been taking place.

Unless something changes, this epidemic could continue indefinitely. Very sad.

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The Lesser of Two What Nows?

It’s been years since I’ve seen the movie Master and Commander: The Far Side of the World, but two scenes stand out in my memory.  One is when the ship’s captain takes the wounded ship’s surgeon, who is also an amateur naturalist, to the Galapagos Islands to recuperate.  The other is the scene with the weevil joke.

Capt. Jack Aubrey: Do you see those two weevils, doctor?
Dr. Stephen Maturin: I do.
Capt. Jack Aubrey: Which would you choose?
Dr. Stephen Maturin: Neither; there is not a scrap a difference between them. They are the same species of Curculio.
Capt. Jack Aubrey: If you had to choose. If you were forced to make a choice. If there was no other response…
Dr. Stephen Maturin: Well then, if you are going to push me… I would choose the right hand weevil. It has significant advantage in both length and breadth.
[the captain thumps his fist in the table]
Capt. Jack Aubrey: There, I have you! You’re completely dished! Do you not know that in the service, one must always choose the lesser of two weevils!

Until recently I had never, to the best of my knowledge, actually seen a weevil, but then I started noticing these tiny insects around frequently.

I do mean tiny – less than two centimeters long.  If it gives you a sense of scale, those crystal-looking things it’s standing on are individual grains of sand.

Thanks to BugGuide, I know now that it’s Pachylobius picivorus, the pitch-eating weevil.  Apparently it feeds on young pines, especially in disturbed areas.  So what was it doing on the beach on the south end of the island, away from the area where most of the island’s pines are?  Maybe the wind blew it here?  I like the dotted line patterns on its back, but I don’t know if they have any significance.

I’m going to submit this post to the beetle carnival, An Inordinate Fondness.  My first time participating!  Also, the second plover from yesterday’s ID challenge remains a mystery – pull out your field guide and take a look! Never mind, the mystery has been solved.  Go look if you’re wondering.

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Elegy for the Red Bay

Dutch elm disease.  Chestnut blight.  Hemlock woolly adelgid.  Emerald ash borer.  It’s the same old story over and over again, and we all know how it goes.

Red bay, Persea borbonia, is a common tree here on the island.  It’s in the laurel family, and yes, it’s related to the bay from which we get bay leaves for cooking; its leaves have a wonderful aroma when crushed.

Most of our red bays, though, are currently sporting as many branches of brown leaves as of green.  Is it because it’s winter?

Peer up into the canopy.  Brown, brown everywhere you look.  Why?

The redbay ambrosia beetle, Xyleborus glabratus, is native to Asia.  In 2002 it was discovered in Savannah, Georgia, and it has been spreading south since.  The beetle brought with it a fungus with which it lives in symbiosis.  The beetle tunnels into a tree in the laurel family, and inside the tunnel it cultivates the fungus, which is its only source of nutrition.  The fungus consumes the tree’s xylem, and the beetle, in turn, consumes the fungus.

And our red bay trees die before our eyes.  The disease is moving south toward Florida, where it will cut the crop of another member of the laurel family, the avocado, in half.

The American elm.  The American chestnut.  The eastern hemlock.  A long list of ash species.  And now, the red bay.

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Stag Beetle

This huge beetle appeared to be dying when we found it on our outdoor stage Monday afternoon.

It’s a male Reddish-brown Stag Beetle, Lucanus capreolus.  Apparently, despite their ferocious appearance, they actually just eat tree sap!