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Apterostigma collare

Posted on May 15, 2011 by Troy Bartlett

4mm | January 19, 2011 | Armonia Nature Preserve, Limon Province, Costa Rica

I spotted the structure below on the underside of a large leaf. I really didn’t know what it was, and I gently poked at it. It was quite fragile as it turns out, and it fell open to reveal an ant nest. I then immediately regretted not having taken a photo beforehand. The next day I was lucky enough to find another one, also pictured.

6cm x 4cm | Unexpected ant nest

4cm x 2cm | Nest with an ant entering

These nests are the work of an ant in the genus Apterostigma. Ants of Costa Rica has an info page for this genus in Costa Rica. I tried to use the key there to identify these, but it was a bit technical for me. I’m basing the species identification on the statements from the site that seem to indicate that only Apterostigma collare builds these nests under leaves. There are some more photos of nests at that same site. read more

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Bullet Ant

Posted on May 9, 2011 by Troy Bartlett

January 19, 2011 | Armonia Nature Preserve, Limon Province, Costa Rica

This species, Paraponera clavata, is the infamous bullet ant. In Costa Rica, its common name is “bala,” which also means bullet. If somehow you don’t already know, the name derives from its powerful sting. Getting stung is said to be as painful as getting shot. I’ve also heard it referred to as “hormiga veinticuatro”, or  24 hour ant, for the duration of the pain. I’m happy to say I can’t testify to any of this personally.

I saw plenty of these large ants. It was difficult to get any images though, as they seem to be constantly on the move. These images were taken at night as the ant crawled around on a tree trunk. read more

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Ant-mimicking Broad-headed Bug Nymphs

Posted on February 25, 2011 by Troy Bartlett

14mm | January 17, 2011 | Cahuita National Park, Limon Province, Costa Rica

At first glance you’d think that’s an ant rather than a true bug. Look closely though and the beak gives it away. These broad-headed bug nymphs (Family Alydidae) were easily found on the same foliage where I saw some Ectatomma ants. Perhaps those ants are the model for this mimic. The caption for this photo certainly suggests that’s the case.

Here’s a side by side comparison.

Mimic, feeding

Model?, waiting in ambush

Notice how the antenna tips are darker in the photo below. I wonder if that makes them appear shorter and closer in length to the model? read more

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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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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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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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