Formica rubicunda journal

I keep a journal of my pet ants over at . The species is a obligate parasite of Formica fusca-group species. Once established in the wild the species will perform raids onto the host species to steal the brood. Every so often I need to go out and find some of the host species brood to give to the parasite in order to keep the colony stable.

View the journal here:



315316Leptogenys punctaticeps

I would see this species, or what I presumed to be this species approximately every week in my study site at La Selva.  I once observed a small colony of 8-10 workers moving in compact single file in the litter and over a log until disappearing into the litter. They were carrying 4 brood items, all of different developmental stages. No morphologically distinct members could be seem. If disturbed, foraging workers are very hard to catch as they run haphazardly and can “disappear” into the litter. Leptogenys in the neotropics is presumed to be an isopod specialist. Most species are nomadic and have a small colony size. For more information see Jack Longinos website here:

317318Leptogenys josephi

This single worker was encountered crossing a dirt path.

Octostruma JTL-005

IMG_1185I had searched this location before and found many foraging Basicerotini workers. They were identified to be Octosruma JTL-005.  I came back here recently determined to find the nest, as little is known about their nesting biology. A quick look under the leaf and stick revealed that the colony was active.IMG_1191I noticed two or three holes that workers would go in and out of. Not wanting to take any chances I gave them a killed isopod(?), and within a minute the scene above presented itself. After about another minute a worker picked it up and brought it down a hole.

IMG_1196I excavated that hole to find a large grouping of workers gathered, some around the isopod(?) and some around apparently nothing. This was quite easy as the workers didn’t react to me pulling back the soil. I was starting to wonder if these ants had an alarm pheromone. I counted three tunnels leading out of this chamber.IMG_1203Pulling back one of the tunnels caused workers and alates to “rush” out of the hole (these ants do not move fast even when distrubed, although the males did move quite fast).IMG_1207Quickly and carefully excavating the roof revealed this. a large chamber approx 2.5 cm in max width, filled with all stages of brood and more alates. I did not collect the colony so I can not say if this species is polygynous or not. The chamber was lined with these weird white specks on the walls.IMG_1211I continued to excavate and found 3 more dead end chambers with brood, workers and alates. When pulling apart tunnels I would see a Pheidole sp. dead or paralyzed, just laying in the tunnels, It looked similar to an active species on the log above. I found five Pheidole sp. workers like this. When excavating the nest chamber I would gather brood by accident too. Another Pheidole sp. found this and started to recruit and attack the Octostruma. I estimate the colony size to be around 300. The nest is near STR 250. Observations made on July 23, 2013 between 1:30pm and 4pm.

A takeover?


The stem pictured above belongs to the genus Ocotea. This genus is an ant plant which normally hosts Myrmelachista sp. ants which nest inside the stem. Two months ago this tree was seen with its normal ant inhabitants. The ant pictured above is not a formicine but rather a myrmicine: Wasmannia scrobifera. The mutualist Myrmelachista ants will defend the host tree from herbivorous insects and other plants while other ants (such as the one pictured above), which just use the hollowed out stems, will not

A Story…

Army ants are abundant in the tropics, and here at La Selva you will probably see them every day if you walk more than a kilometer or two on the trails.


This is the trail to my field site where species of Eciton frequents.  I have tried to follow their trails into the forest before, but it usually becomes too thick with undergrowth. I have also collected Labidus and Nomamymex in this area.

ImageThis trail was quite conspicuous as the ants were carrying prey brood across the trail. To find the bivouac all that needed to be done was to follow the trail in the direction of the brood… for less than one meter.



With the bivouac found, I decided to follow their trails and see what their raid front was like. When going through the undergrowth, one must be constantly aware and on the look out for snakes and the bullet ant among other things, such as this fuzzy dangling caterpillar. ImageI followed the trail along logs, over logs, through logs and once under a log, fun stuff. These army ants Eciton hamatum or Eciton lucanoides have only one eye facet and as such are only able to sense the amount of light with no directionality. They can only communicate with smell (If there is evidence of any tactile communication in these ants please provide it) which is why their antennae move so rapidly about.



Innevitably when coming into contact with the flora, creatures will get onto you. Thankfully this time it was just a Cephalotes cristus. It could have just as easily been the bullet ant aka Paraponera clavata fabled for its powerful sting.

IMG_1142 IMG_1141



Coming to the raid front I find this scene. A “soldier” ant stands at the entrance of the nest of some creature. Unfortunately I did not see them carry out any brood.  IMG_1157

The army ants were swarming this small patch of litter next to the walk way where the photo was taken. I observed them here for ~15 minutes. When the swarm subsided and they moved on, I looked into the litter and saw many small ants running around. Turning over a random leaf revealed a small colony (fragment?) of Pheidole hirsuta. with brood.


Here an Acromyrmex octospinosis. carries its brood up the vegetation in order to escape the incoming army ants. When this ant ran up the palm leaf it ran right by and through a sparse trail of the army ants.IMG_1163

The Acromyrmex sp. worker carrying this brood was not as lucky (the brood itself was unluckier). At this point I decide to head back.


Several very large bees were around a recent branch fall, 2 meters from the bivouac.

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