When you think of a caterpillar, your mind usually turns to an image of a plump little grub-like insect with stubby legs, happily munching away on a leaf. But caterpillars in the jungle don't mess around. Surrounded by predatory spiders, ants, birds and lizards, it's a wonder how any caterpillar reaches its final butterfly or moth form.

While many caterpillars remain remarkably cryptic, blending in with their environment, some take the opposite approach. Evolution has carved out warrior-like caterpillars that don spiny armor plastered in bright warning colors. To pack on an extra punch, many of these caterpillars harbor venom-tipped spines that will leave the attacker, or unfortunate human, with a painful skin rash and in some cases even death.

I'm always fascinated yet cautious when I encounter these caterpillars in the wild, so here are some of the coolest looking Lepidoptera larvae I've encountered trekking through the Peruvian Amazon.

67 Questions About The Amazon Jungle - Amazon Wildlife Photography Book

A tree covered with strange yellow bulbs in the jungle

A closer look at the mysterious yellow "bulbs"

An unknown caterpillar eating one of the yellow bulbs

I quickly noticed there were also ants surrounding these caterpillars. The ants were not attacking the delicate butterfly larvae, so this had to be some sort of symbiotic relationship between the caterpillars and ants. While I had little idea at the time what I was looking at, my background in entomology was telling me one thing: this was something cool.

An ant, Ectatomma tuberculatum, guarding a caterpillar

Always gotta show a finger for scale

An attendant ant tapping the caterpillar and receiving a nectar droplet. Filmed thanks to the help of Chris Johns

A butterfly with a yellow wing spot lands on the tree

• Mysterious yellow bulbs growing on a tree
• Caterpillars eating the yellow bulbs
• Ants taking care of the caterpillars
• Butterfly with yellow wing spot lands on tree with yellow bulbs

I assembled the photos from the trip and starting emailing the top butterfly experts as well as botanists. The responses I received were mostly along the lines of "I've never seen anything like this before" and "there's nothing published on the life history of the butterfly". Ok, so it seemed like we were on to something new here.

An ant protecting two young caterpillars

With the help of some experts, we were able to identify the butterfly as Terenthina terentia, which belongs to family Lycaenidae. While this family contains around 6,000 species, the Neotropical lycaenids are still only partially known and poorly studied (Pierce 2002). Many species of lycaenids are known to engage in relationships with ants (aka myrmecophily) so our caterpillars definitely fit this criteria.

Filming this strange caterpillar-ant-parasitic plant relationship

Several botanists emailed my pictures around to their colleagues until we were finally able to ID the yellow bulbs as a "very unusual and rarely seen"parasitic plant belonging to the family Apodanthaceae. Ever heard of that? Yeah, me either.

The yellow bulbs later identified as a rare flowering parasitic plant

In January, my colleague Phil Torres visited this site and checked out the caterpillars. You can see the yellow bulb flowers are more developed at this point.

Compilation shots of a potential Terenthina terentia caterpillar showing its morphology

Perhaps the yellow wing marking helps the butterfly blend in with the yellow parasitic plant and reduces predation by birds. While this hypothesis needs further attention, the similar wing pattern and observed host plant could lend support to the idea of a long-term co-evolutionary relationship between the flowering endoparasitic herb and the Terenthina terentia butterfly. In any case, we'll attempt to continue to pick apart this fascinating Amazon mystery which will undoubtedly result in even more questions!
Bellot S, Renner SS (2014) The systematics of the worldwide endoparasite family Apodanthaceae (Cucerbitales), with a key, a map, and color photos of most species. PhytoKeys 36: 41-57

Pierce NE, Braby MF, Heath A, Lohman DJ, Methew J, Rand DB, Travassos MA (2002) The ecology and evolution of ant association in the Lycaenidae (Lepidoptera). Annual Review of Entomology 47: 733-771
 

I've been fortunate this past year to log so much time in the Amazon rainforest. It can be a tough environment for extended trips; it's hot, you're in a perpetual state of sogginess from the humidity and sporadic downpours, and there are bugs constantly attempting to withdraw your blood. With that being said, the Amazon rainforest is also an unbelievably amazing place, as the jungle hosts some of the most incredible views and creatures I've ever laid eyes upon. Below you'll find a selection of my favorite jungle critter encounters from 2015, hope you enjoy!



First up, my favorite reptile encounter also happens to be the most potentially dangerous encounter. Credit goes to my girlfriend, Bri, who joined me in September and quite literally stumbled upon the Pit Viper, Bothrops atrox.



Commonly known as the lancehead, this snake claims the most lives each year in South America due to its deadly venom. We kept a safe distance while snapping photos until both us and the viper walked (and slithered, respectively) our separate ways.



My favorite rare mammal has to be a toss up between the Tapir and the Tayra. Both are quite elusive animals and are rarely seen, even by the locals. This counts as my second Tapir sighting - we were lucky to be so close as she was crossing the river at around 4:30 in the morning while we were on our way to the Chuncho clay lick in October.



The tayra is an omnivorous animal from the weasel family. We spotted this one in October near the Posada Amazonas jungle lodge while he was sneaking around searching for discarded apples.



While I have yet to spot a big cat in the wild, we have captured many amazing cats on a camera trap that I helped Jeff Cremer set up a few months ago, including Jaguars, Pumas, and Ocelots. (see more of Jeff's camera trap photos here: http://gizmodo.com/how-dslr-camera-traps-are-capturing-stunning-wildlife-p-1730499208)

Up next are my favorite bugs (of course). The Amazon rainforest contains the most species of insects on the planet, so as an entomologist it's really hard to play favorites. My top 3-way tie are surprisingly all caterpillars! I never considered myself to be a butterfly/moth guy, but the Amazon has quickly changed that. There seems to be no end to how strange caterpillars come in shape, size, color, and behavior in the jungle.



In March 2015, I accidentally stumbled upon a caterpillar that would become one of my most popular critter stories. We called it the "tentacled caterpillar", as it had four tentacle-like structures on its back that would "pop out" when alarmed by the sound of our voices (no, seriously).


You can watch the video: Crazy Tentacled Caterpillar in Tambopata, Peru

 

Next up, in my opinion, is one of the coolest discoveries I've come across in the rainforest. Several months ago, I found a tree with bizarre yellow outgrowths. Upon closer inspection, I realized there were caterpillars munching on these yellow "bulbs" and ants were taking care of the caterpillars.



Immediately, I knew this had to be an unusual observation and indeed, it turned out to be a never-before-seen relationship and life history for a rare butterfly.


You can watch the full video: Mystery of the Yellow Bulbs: Caterpillars, Ants & Parasitic Plants



Finally, we have the slug moth caterpillar. Not a very attractive name for a beautiful insect larva. Spotted in May near the Posada Amazonas lodge, I can only imagine what purpose the groovy color pattern serves.



My favorite tiny critters have been viewed through a handheld origami-style microscope that I was fortunate to test out in the Amazon rainforest starting in March 2015. Known as the Foldscope, we've observed all sorts of strange and interesting animals and structures belonging to the microcosmos including butterfly wing scales and unknown mite species.

A compilation of butterfly wing scales I’ve sampled with the Foldscope

You can watch the full video: Foldscope in the Amazon Rainforest



My favorite bird encounter has to go to the Harpy Eagle. These amazing apex predators are rare to spot in the wild, let alone view one of their nests. In May, Jeff and I climbed 100 feet up into the canopy to photograph and film the chick before it left the nest.


You can watch the video: Journey to a Rare Harpy Eagle Nest

 

I would be remiss if I didn't include a photo of the incredible gathering of macaws and parrots at the clay licks. No other place in the world like this!

 

My favorite fungus award goes to none other than the weird Clathrus ruber, which looks like something a 3-D printer messed up.



Finally, my favorite strange animal interaction has to be butterflies drinking turtle tears. They mob the unsuspecting turtles likely to gain extra nutrients such as sodium.

Overall, it has been a busy and incredible year to say the least. I owe a huge thanks to Rainforest Expeditions and the ecotourism that makes all of this work possible. While this post was about my favorite critter encounters, the people who joined me make these trips truly special. I've been joined by friends, family, researchers, science writers, photographers, and more, making every trip unique.

So last but not least, here's a quick shout out to my favorite human critters of 2015.

Filming the Harpy Eagle nest with Jeff and Frank in May

On the way to the Tamboapta Research Center in May with my parents

Waiting patiently at the clay lick in July with Jason, Jeff, Fernando, and Cat

Hopping on the boat with Bri, Lucas, and Hayley in September

Exploring abandoned biological stations with Jeff, Nadia, Elizabeth, Cintia, George, and Zoltan in October

Last but not least, closing out December with Christina and Derek