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Leafcutter Ants Nesting Above Ground

Posted on February 20, 2011 by Troy Bartlett

January 17, 2011

Cahuita NP, Limon Province, Costa Rica

I was watching some leafcutter ants and I noticed they disappeared inside the trunk of this tree palm(?). I thought perhaps they were just passing through, but another trail ended on the other side.

In the second photo you can see some leaves being carried along one of those stems. One of the nest entrances is about one third from the left and one third from the bottom.

I thought that leafcutter ants always had underground nests. Perhaps that’s the case here as well, with the majority of the nest still being underground. It’s a swampy area though, and the area behind the tree was submerged. It makes me wonder how leafcutter ants nest in areas that are often inundated with water. read more

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Trapjaw Ants

Posted on February 19, 2011 by Troy Bartlett

10mm | January 17, 2011 | Cahuita National Park, Limon Province, Costa Rica

Not great shots, but I wanted to post these shots of some trapjaw ants, Odontomachus erythrocephalus. While taking the first photos of my trip, I knelt down on a log on the side of the trail in order to steady my camera. A few seconds later, I was stung by one of these guys on the inside of my knee. Turns out they had a nest in that log, and they weren’t happy about being disturbed. They don’t seem to like to expose themselves though, and I had a hard time trying to photograph them once they painfully made me aware of their presence. read more

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Ectatomma tuberculatum

Posted on February 17, 2011 by Troy Bartlett

12mm | January 17, 2011

Cahuita NP, Limon Province, Costa Rica

These ants, Ectatomma tuberculatum, were easily found on the vegetation shown above. Not sure what the plant is, but it dominated the coastal trail near Puerto Vargas within Cahuita National Park. The white plant parts shown attracted quite a variety of critters. I think the ants above (possibly the same ant) are waiting in ambush. Below, I tried to catch one on the move.

Dorsolateral view

I found an interesting story while reading about this ant. A USDA biologist, O.F. Cook, was convinced this species could help control the impact of boll weevils on cotton production. In the early 1900’s he introduced it to cotton fields In Texas, but it failed to colonize. read more

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Leaf Beetles and Damaged Leaves

Posted on February 16, 2011 by Troy Bartlett

2mm | January 17, 2011 | Cahuita National Park, Limon Province, Costa Rica

This is almost but not quite the shot I was going for. When I first saw this little beetle it was oriented toward the freshly eaten patch. With the frass strewn around, you can just imagine it chewing away at the surface in a circular pattern. I wasn’t quite stealthy enough in my approach however, and I spooked it into moving away.

Below is a similar beetle, perhaps a different sex of the same species. Note the difference between the freshly eaten patch above and the older ones below.

Showing older leaf damage

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Cephalotes basalis

Posted on February 15, 2011 by Troy Bartlett

7mm | January 17, 2011 | Cahuita National Park, Limon Province, Costa Rica

If I managed to use this “Key to Cephalotes Species Known from Costa Rica, Based on Minor Workers” correctly, then these images are of Cephalotes basalis.

There were quite a few crawling around on low vegetation.

Dorsal View

One interesting thing about this arboreal genus is that some members (perhaps all) have the ability to glide during free fall. If they fall, they use this ability to attempt to maneuver themselves toward their host tree trunk where they have a much better chance of returning to their nest. read more

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Mating Snout Beetles

Posted on February 14, 2011 by Troy Bartlett

2mm | January 17, 2011 | Cahuita National Park, Limon Province, Costa Rica

These beetles are tiny. Each one is only a few millimeters long.

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Reddish Tortoise Beetles

Posted on February 13, 2011 by Troy Bartlett

4mm | January 17, 2011 | Cahuita National Park, Limon Province, Costa Rica

There were quite a few of these reddish tortoise beetles feeding on this banana plant.

Banana plant

They feed on the large leaves, scarring them in a distinctive way.

Sign from feeding

Here you can see one munching its way forward, carefully feeding only between the leaf veins.

Machinelike feeding precision

Did you notice the little hitchhiker above? Looks like some sort of parasitic wasp to me. I suspect this is probably a female beetle, and the wasp is just hanging out until she lays eggs, which the wasp will then parasitize. Here’s a closer look.

Parasitic wasp closeup

They’d often fly away from me once I started taking pictures, but it was no trouble to find another one. read more

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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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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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