On Wednesday, a very hungry caterpillar did not eat through one apple, two pears or even three plums. He instead ate along the outside of a green leaf towards the narrow tip until only the main vain was left. He then barricaded himself behind a wall of his poop and dangled on the edge of the leaf with the forest floor – and certain death – far below.
Not far away in the same forest, graduate student Cassidi Rush’s eyes dart back and forth along the wet jungle trail as she looks for just such a caterpillar – no bigger than a grain of rice – and the colorful butterfly it changes into. Her dark hair is pulled back through a ball cap and her boots are caked in fresh mud. She carries a large butterfly net in her hand while a pair of binoculars bounces around her neck.
“Ahh!” something catches her eye. “Sorry I don’t go very far before end up stopping,” she says. “It drives my field assistant crazy.” She reaches out over the side of a small moss-covered bridge and pulls on a branch for closer inspection. “Nothing on this one.”
You wouldn’t expect it, but not long ago Rush was inspecting children’s teeth for cavities, listening to how they swear they floss twice a day through a mouth full of cotton balls. The sterile environment of a dentist’s office seems far removed from the humid jungles of Costa Rica – but neither, it seems, is without danger.
“Sometimes they bite,” she laughs, referring to her former patients. “Luckily it hasn’t happened to me”.
Cassidi’s family always expected she and her five siblings would move home to Phoenix, Arizona and work at the family dental practice. While already halfway through dental school and with patients of her own, she put down the drill and Novocain and decided pick up a biology book. She didn’t want to be “that girl that cleans peoples teeth.” She explains she needed a change: to do something important in her life and for the planet, to blaze her own trail. Wildlife conservation would become her passion, fulfilling a desire to be challenged and study biology.
An unpopular decision with her family to be sure – but Cassidi pressed on, reuniting with an influential professor from her past; an ecologist by trade who taught anatomy and physiology to would-be dentists at the University of the Pacific. He was ecstatic to have a former student return and become interested in his field of study. Shortly thereafter he sent his new pupil out into the tropical rainforests of Costa Rica to snatch up butterflies.
This summer at La Selva Biological Station, Cassidi is exploring the diversity of life along a “latitudinal gradient.” Put simply, life is more diverse as you move from the poles to the tropics. Cassidi along with her team hopes to illustrate this by comparing a certain type of butterfly, Adelpha, in the jungles of Costa Rica, Ecuador, and Panama to similar butterflies captured in California. They’re essentially taking a butterfly census.
In the tropics Cassidi and her team have found nine species of Adelpha, whereas in California they have come across only one. The difference is those nine tropical species, however, do not appear in the same numbers as its single northern cousin.
The numbers of butterflies caught so far in Costa Rica are also not as high as she expected, and this may be because catching a butterfly is not as simple as it sounds.
She’s strategically arranged traps around eight miles of La Selvas flooded swamps. Each site contains two traps, one barely visible high in the canopy amongst a sea of green and piercing skylight, the other, in the understory much closer to the forest floor. Months earlier, Cassidi and her team used comically large slingshots to launch a rope over the skyscraping branches of the forest canopy.
“It basically takes all of my body weight to pull it down!” she jokes. “When I do it I have to sit on my butt and lift my feet up because my arm strength isn’t good enough to pull it down all the way.”
Once the rope had found its purchase, she hoisted the homemade butterfly hotels skyward with a simple pulley. They look like a child’s drawing of a rocket ship – a long hollow tube made of soft mesh to contain the captured butterflies and a pointed plastic top to shield them from the constant tropical rain. Baits high in salt sit in a platform at the base – the proverbial dinner bell for hungry butterflies. Some are outfitted with rotting fruit like the ever-popular banana, while others have a variety of unusual meats on the menu. But it seems the butterflies at La Selva are picky eaters. What has worked elsewhere is not working here and like a chef, Cassidi is trying to prepare a meal to attract more customers. The latest entrée she’s serving up – scraps of shark flesh.
“Apparently in Ecuador when you put the shark bait in the traps they were full of butterflies” she says. Researchers “were tossing samples out because they had too many.”
Another scientist on her team discovered this while working in Ecuador and Cassidi wants to apply this knowledge in the field at La Selva. It is apparently a longstanding practice for locals and guides in Ecuador to use rotting shark meat in this way to draw in butterflies for eager tourists. It smells awful but gets the job done. She hopes this new tactic will work as well in Costa Rica and attract enough butterflies to capture a large enough sample size to finish her research.
A few years removed from dentistry and Cassidi hasn’t looked back. Though her family was initially stunned – her parents didn’t speak to her for a couple weeks, she jokes – they now support her decision to change professions and pursue wildlife conservation. She has taken an unlikely route on the path towards following one’s own passion. Like the butterflies she studies, Cassidi Rush transformed herself.