Agrias Foodplant

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On a wet and semi-humid afternoon in the jungles of Costa Rica, I discovered
something that I thought would have taken me at least another 3-5 years of
exploration in the tropics to find. An Agrias amydon philatelica caterpillar.
Although lacking in color, the larva of the Agrias is no less interesting than
the beautiful and iridescent colorings of the adult. In fact, the Agrias
caterpillar has so much personality, that I have trouble believing that it is
just a caterpillar, or perhaps I now have more respect for caterpillars in
general.  

I had practically given up all hope of making the discovery, as a couple days
earlier, I located its foodplant (Erythroxylum havanense) with no signs of the
very distinctive looking larva. Agrias caterpillars are very similar in shape
to Prepona larva, with a conical shaped head, two tails in the back, a
hunched-up thorax and, except for a few small warts and spots which I believe
are mimics of parasitic wasp eggs, the body is relatively smooth. Discovering
the plant was actually exciting enough, but to see the caterpillar was the
real goal. I had spent countless numbers of hours in libraries and museums
trying to get a feel for what the plant looked like, but when you finally get
out and go trekking in the jungle, faced with thousands of plants to choose
from, the search becomes quite difficult.

The morning of the discovery, I was beginning to question the journey. All of
the time and energy spent in search for a glimpse at one of nature's most
beautiful species. Other people in Costa Rica were visiting spectacular
volcanoes, basking in the sun on white sandy beaches, surfing, snorkeling, and
dining, and here I was, lifting up Erythroxylum havanense leaves in the hot
and steamy jungle looking for a caterpillar. The day had started out with a
horrendous storm. There was a tremendous amount of rain. Thunder and lightning
were so close (5 feet away) that my car shook while parked next to the jungle
entrance. I remembered reading that if hit by lightning while in a car, the
lightning would disperse throughout the car's chassis (if properly grounded)
with no risk to passengers, but somehow the noise and strength of the thunder
were smashing any bit of solitude gained from that article. I looked around to
determine that I wasn't parked in a potential flood trap, and continued
waiting in the car for the rain to subside. An hour later, I took one last
walk through a jungle trail, which looked and felt like the garden of Eden. I
walked for a while along a stream and came across an E. havanense plant that
looked perfect for an Agrias. In fact, I said to myself that if I were an
Agrias, I would definitely lay an egg on this nice plant located so
strategically near the stream with plenty of exposure to sun. And there she
was, a fifth instar Agrias caterpillar, hunched-up and resting on a thin
branch at an angle. The caterpillar in some ways stood out so blatantly as it
had no resemblance to the leaves or stems of its hostplant, and then I
realized that it was mimicking a larger dried out canopy leaf fallen from
above. The caterpillar also had a wobbling gate when it moved, resembling a
dried leaf shaking in the wind.

Well, the discovery made the expedition worth while, and I was now no longer
thinking about volcanoes and girls on the beach. Later in the trip, I ran out
of foodplant and substituted Erythroxylum coca, the only other Erythroxylum
species available at the University. E. coca is used to process cocaine, and
is also used to process legal medications including Novocain, etc.
Lepidopterists including Phil DeVries have speculated that Agrias feed on E.
coca, along with other species of Erythroxylum. This speculation is now
confirmed. There are more than 250 species of Erythroxylum, and only two
species contain enough cocaine alkaloids to produce the illegal drug. It is
still unknown as to whether or not Agrias gain any predation defenses from the
alkaloid. 

I hope to publish a paper on the specifics of the rearing, but a female Agrias
amydon philatelica did successfully emerge 17 days after pupation.


Jim Hanlon