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Army Ant Week Post #3

Posted on February 10, 2011 by Troy Bartlett

January 23, 2003 | Rincón de la Vieja National Park, Guanacaste Province, Costa Rica

OK, I admit it’s not a great photo. What I was trying to show here though was how thoroughly the army ants at the raid front carpet an area, looking for prey. They go in, under and over everything. I usually just step over the raid trails when I encounter them. In this case though, they were very thoroughly blocking the trail I was on. I eventually tip-toed through them, followed by some vigorous foot stomping.

Seeing a raid front really is quite a spectacle though. There are often antbirds flitting around, and it’s amazing to see all the stuff that the ants scare from the leaf litter. I’ve been surprised by just how many hidden critters are suddenly forced into revealing themselves. As potential prey flees the ants, you can’t help but notice how some are immediately set upon by parasitic flies. read more

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Army Ant Week Post #2

Posted on February 9, 2011 by Troy Bartlett

July 20, 2006 | Ilhabela, Sao Paulo State, Brazil

These two photos are from my first trip to Brazil. I spent a week on the island of Ilhabela, a few hours drive from Sao Paulo.

I probably wouldn’t even have noticed these ants if not for the calling of antbirds. The birds were making quite a fuss so I moved in to investigate. That’s when I started to hear a light rustling noise and then noticed the ants carpeting the leaf litter. The rustling is not just the ants, but all of their potential prey trying to escape.

Below, they’ve managed to overwhelm a spider, er, well, actually just a shed spider skin. Honestly, I always believed this was a captured spider until reviewing it yesterday when I noticed something was off. read more

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Army Ant Week Post #1

Posted on February 8, 2011 by Troy Bartlett

In honor of Army Ant Week, I’m going to take a short break from my recent Costa Rica photos to post a few army ant photos.

June 7, 2004 | Barro Colorado Island, Panama

The only time I’ve ever seen an army ant bivouac was on a trip to Panama. I don’t recall if the photo above was of part of the bivouac or just an ant bridge somewhere along a foraging trail. My field notes were unfortunately lost in a house fire several years ago.

This could be Eciton hamatum, based on Alex Wild’s post today on that species. They are definitely orange, and I don’t recall being bitten or stung. If they are some other species, I’m sure I’ll be set straight in short order. read more

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Ant, Victimized by Fungus

Posted on February 7, 2011 by Troy Bartlett

Ant, 10mm | Fungal stalk, 5mm | January 17, 2011 | Cahuita National Park, Limon Province, Costa Rica

This unfortunate ant fell victim to a fungus, Cordyceps perhaps.

This short sequence from an episode of the Planet Earth series gives a nice introduction to the phenomenon.

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Velvet Ant

Posted on November 7, 2010 by Troy Bartlett

January 27, 2010 | Caraça Natural Park, Minas Gerais, Brazil

I like finding velvet ants, but boy are they tough to photograph in the field. They don’t stand still unless they’re hidden. This crop is the best I could do for this one. I saw one other one like this.

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Identification Challenge #3 Reveal

Posted on November 5, 2010 by Troy Bartlett

Chris Grinter agrees with me that this photo is of a sawfly in the genus Dimorphopteryx.

June 6, 2010 | Twelvestones, Roswell, GA, USA

I first saw some photos of similar sawflies in this book:

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I then found some images on BugGuide.

It really is an odd looking critter. If I’d instead shown this view, it would have been more obvious, I think, that it’s a sawfly.

Side view

Here you can see the horns just behind the head.

Closeup of head

Marshall reports that the “tubercle behind the head is eversible, and sticks out like a snake’s tongue when the insect is disturbed.” Cool. I wish I’d known that when I encountered it. I would have tried to coax it into displaying that behavior. read more

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Pelecinid Wasp

Posted on November 1, 2010 by Troy Bartlett

January 28, 2010 | Caraça Natural Park, Minas Gerais, Brazil

Wasps in the family Pelecinidae are distinctive and easily recognized by that long thin abdomen. I’ve see them closer to home as well, but I can’t recall if I’ve ever gotten a decent photo. I do remember chasing after quite a few in vain or watching as one teased me from someplace just out of reach. I got lucky with this one.

What I thought was a red marking turns out to be a small mite.

There’s only one genus, Pelecinus, for this family. There appears to be at least two described species in the tropics. read more

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Some Army Ant Observations

Posted on October 31, 2010 by Troy Bartlett

January 27, 2010 | Caraça Natural Park, Minas Gerais, Brazil

That’s the general scene. I encountered these army ants on the side of the trail towards the end of the afternoon. The odd thing is that I didn’t see much more than what’s shown here. There were a couple of holes in the ground, outside the shot above, but roughly in the upper left and lower right. Despite some searching in the nearby vicinity, I didn’t find any other ant trails. But there were ants streaming in and out of the two holes, forming roughly two paths. The bottom path was moving to the right and the top to the left. read more

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Unexplained Beetle Behavior

Posted on October 30, 2010 by Troy Bartlett

January 27, 2010

Caraça Natural Park, Minas Gerais, Brazil

This beetle looks like a buprestid to me. The interesting thing is that it’s splitting this leaf lengthwise. In the second photo, you can see where the cut starts in the upper right. That would seem like an odd way to eat, so I suspect there’s some other purpose. Is anyone familiar with this behavior?

There’s also what appears to be a small wasp hanging out on the elytra.

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Ants Herding Treehoppers

Posted on October 18, 2010 by Troy Bartlett

January 28, 2010 | Caraça Natural Park, Minas Gerais, Brazil

These ants have quite effectively corralled their herd of honeydew producing treehoppers.

There’s a lot to see here if you look carefully. First, it looks like quite a few of the life stages of the treehoppers are present. There’s the dark adult in the center, an early instar in the bottom center, and the majority appear to be middle instars.

In the detail below, you can see the ant on the right has just taken a drop of honeydew and the dark adult has a drop waiting.

Detail

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