Army Ant Week Post #3

February 10th, 2011 - 5:54 PM | Filed under Featured Photos | No comments

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.

Army Ant Week Post #2

February 9th, 2011 - 6:34 PM | Filed under Featured Photos | No comments

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.

Not quite the juicy meal they'd hoped for

Army Ant Week Post #1

February 8th, 2011 - 8:25 PM | Filed under Featured Photos | 6 Comments

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.

I encountered some army ants on my recent trip to Costa Rica, but I gave up on any photos. The few times I approached a column, they quickly started swarming up my boots.  It almost seemed like they had a sixth sense or something. Even though I wasn’t in their direct path, they always seemed to gravitate towards me.

I have some other army ant photos that I’ll try to post before Army Ant Week is over.

Also, don’t miss these army ant observations from about a year ago. At least I think they were army ants. I keep waiting for someone to tell me they were something else.

Some Army Ant Observations

October 31st, 2010 - 11:06 AM | Filed under Featured Photos | 8 Comments

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.

Usually when I encounter army ants, I’m hesitant to get down on my hands and knees and start taking pictures. I’m always afraid they will branch off in my direction while my vision is reduced to what’s in the viewfinder, and the next thing I know I’m covered in them. Having said that, army ants don’t generally give me much pause. Even if they have spread out across the trail, it’s pretty simple to just walk right through them.

On this occasion, they seemed pretty contained, so I sat down and started looking closer. It didn’t take long before I started seeing some myrmecophiles (things that live among the ants). Mostly I saw these:

Myrmecophile

Like the ants, they are fast moving and difficult to photograph. I’d spot one, but it would then be hard to frame it. I decided to mostly keep the camera trained on one of the holes, wait to spot one approaching, and then try to get a picture of it before it disappeared underground. What you see above is the best shot I managed to get of one. I believe it’s a beetle, a rove beetle perhaps.

I also occasionally spotted ant pupae being transported.

Ant pupa

Another ant pupa

Here’s one of the larger soldier ants.

Ant soldier towering over workers

Darkness was approaching, and then something unusual happened. The scene became one of chaos as the paths all but disappeared and instead the ants just sort of carpeted the area. Then, paths became discernible again, but the ants had switched directions!

I would have loved to have watched longer, but there just wasn’t enough light so I continued on the path back towards the sanctuary.

I know that some species of army ants are subterranean, so perhaps these are one of those species.

References:

Latin American Insects and Entomology
by Charles L. Hogue
American Insects:
A Handbook of the Insects of America North of Mexico

by Ross H. Arnett, Jr.