Abejones de Mayo — or May Beetles — crawling and buzzing on people’s porches in Costa Rica signify the start of the rainy season. They are also provide many benefits to the country’s ecosystem. Not only are they pollinators and prey for other animals, they also recycle nutrients and their excrements can serve as fertilizers.
But for the past three decades, their population has declined. There are many reasons but one of the biggest is light pollution.
After a leisurely run through the Sarapiqui area of Costa Rica, Henry Alfaro Lara returned to his home. Lara works and lives in Aguas Bravas, a popular spot for river rafting. Sitting on a wooden bench by the Sarapiqui river surrounded by palm trees and the sound of the gentle flow of the water, Lara reminisced about his childhood. He recalled beetles showing up at night, hanging around the only light in his house.
“Estábamos ahí como viendo por la casa ahí donde se cachaban ahí en los postes de la casa entonces estamos conmocionados y ver esos meros bichotes bien bonitos,” Lara said. (“We’d be there, looking all around the house, watching them as they latched onto the posts. We were just mesmerized, gazing at those massive, truly beautiful bugs.”)
He said when he was five years old, he and his friends knew when May came around, because the beetles would arrive. They were always impressed by its size as it buzzed and crawled on their porch.
However, he said it has become harder and harder to spot these glossy brown species.
La Selva Research Station sits in a 4,0000 acre tropical rainforest in Sarapiqui. Danilo Brenes Madrigal, a taxonomist who studies living organisms and biologist, said beetles are nocturnal species easily attracted to artificial lights.
He said they fly and fly continuously throughout the night and either die from exhaustion or birds end up eating them.
“Entonces, si hay una concientización por parte de las personas de querer conocer más y cómo ayudar a que no suceda,” Madrigal said. (“So, if there is an awareness among people, a desire to learn more and to understand how to help prevent this from happening.”)
Research shows when beetles fly by a light bulb at night, their instincts force them to tilt their back toward the bulb until they get stuck in dizzying loops.
Dr. Jennifer Birriel, a physics professor at Morehead State University, says because nocturnal species are attracted to blue and ultraviolet lights, using old-fashioned low or high pressure sodium or HPS lights is preferable. She says these lights emit very little blue light compared to an LED one.
“It’s a growing problem that we have to get under control, for even ourselves, we have to have food to eat, if we don't have insects that are pollinating, then we're not going to have our agricultural source,” Birriel said.
She said change can start in your own home. Properly shielding lights so it’s directed downward and using motion sensor lights are a couple ways to help the beetle population.
Back in Sarapiqui, Henry Alfaro Lara hasn’t lost hope for the May beetles.
“Creo que poco a poco vamos creciendo y se pueden lograr muchas cosas,” Lara said. (“I believe that, little by little we are growing, and that we can achieve a great deal.”)
He said by changing the lights on the streets and homes in Sarapiqui, the friction between human and wildlife can gradually disappear.
