Parque Amboro – Jurassic-era ferns and formic acid from fire ants in the Cloud Forest

My first hike in Samaipata was into Parque Amboro, aka the “Cloud Forest.”


The forest is covered with a dense layer of clouds, which thankfully didn’t rain on us that day.

Before we had even entered the forest our guide pointed out perhaps the most interesting site of the hike, a huge anthill constructed by fire ants.


Indigenous tribes still living in isolated parts of Bolivia use the formic acid from the fire ants to kill young children’s parasitic stomach infections, such as Giardia.

To isolate the formic acid without having to suffer several nasty bites the tribes poke a stick into the side of the fire ants’ nest, as the guide does in this video here.  In the video you can see the strength of the fire ants’ bite.  When the guide gets a couple on his hand he must delicately and painfully pull them out after they have chomped into him, and you can hear him yell in pain while he does.

In most situations, ramming a stick into a meter-high mound to enrage the thousands of fire ants inside is a bad idea.  But if you’ve got a stomach bug in the forest, it may be your best bet.  The fire ants madly attack the stick by biting it repeatedly, then spraying formic acid into the wound they believe they are creating in the stick.  This leaves the tip of the stick covered in the ants’ potent formic acid.  The acid gives off a very pungent aroma that resembles spearmint.

To ingest the formic acid the tribes would simply have their children suck on the end of the stick that was attacked.  Once ingested, the formic acid would eradicate the parasites in the stomach and usually within a day or two the child will be feeling better.

If I had known that at the time I was developing Giardia, I may have considered having a taste of the stick myself.  It goes without saying that killing a stomach bug with formic acid from a fire ant is a way better story than taking Tricomicin…

The fire ants weren’t the only venomous insect in Parque Amboro.  There were also lots of these beautifully dangerous caterpillars.

Look but don’t touch!

Look but don’t touch!

At one point our guide somehow ended up with one on his cap and inadvertently touched it while trying to brush it off.   Ouch!  The spines of the caterpillar are toxic but not lethally so.

Not all the insects in the forest were dangerous.  According to our guide this grub is considered a delightful snack by most indigenous tribes in Bolivia.

Thanks, I’ll pass….

Thanks, I’ll pass….

Parque Amboro is best known for its massive fern trees.


The fern tree species that grow in Parque Amboro date back to the Jurassic Period.


The tree ferns are big and tall, keeping the forest cool and shaded.



A picture our guide took helps put the size of these big tree ferns in better perspective.


The lichen growing in Parque Amboro on the trees are 50 shades of grey green.


Trekking through the forest requires wet slides down some cold muddy slopes and treks up some equally slippery streams.

Matan carefully makes his way up the stream

Matan carefully makes his way up the stream

I fell down at least five times on this hike and by the end of the hike, my hands were thoroughly covered in mud.

Yoel assures me that we will be rocking out in no time

Yoel assures me that we will be rocking out in no time

To complicate the slippery hiking, you must resist your instinct to grab onto nearby trees for support.  The trees are covered with spiky thorns, a defensive evolutionary advantage that likely dates back to the Jurassic Period.


I made the mistake of grabbing one of the trees for support on more than one occasion.


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