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In Costa Rica, when a person is disoriented and collides awkwardly with the objects around him, he is told that “as a bare of May.” This is a reference to the beetles of the genre Phyllophaga that Costa Ricans have historically associated with the beginning of the rainy season, which extends approximately eight months. In May, during the first rains, these spare parts leave the earth to try to reproduce during the last weeks of their life cycle of just one year.
Andrés Arias, 27, remembers how these insects abounded in his house in the canton of Montes de Oca when he was a child and the way they collided with the walls at night, confused by the artificial light of the bulbs. Now, as a biologist and researcher at the University of Costa Rica (UCR), he regrets that May Abejones, a name with which more than 400 species of beetles are popularly called, are an increasingly common sighting.
“It is something that is noticed by collecting them and it is very sad. I start thinking if, within a few decades. The new generations will even understand the saying of the bares of May,” the expert tells future America, which works as in charge of the scientific collection of the UCR insect museum.
Although there are no official data on the decrease in Abejones, the biologist Ricardo Murillo, also a professor at the UCR, estimates that he approaches a loss of 95% of these species in 40 years. Arias does not dare to conjecture on an exact number because in the university they have not yet done studies on their population over time, but coincides with their colleague in the cause of this phenomenon: the loss of habitat due to urbanization.
This hypothesis is based on the fact that the absejones larvae that inhabit under the ground need to feed roots. “Then, if we increasingly replace the green areas of gray work, concrete and rod, we are talking about an environment in which a May Abejón will not prosper,” says Arias.
Costa Rica has gone through a rapid urbanization process in recent decades that has resulted in abundant buildings of buildings in the so -called Great Metropolitan Area. According to World Bank data, the Costa Rican urban population went from 50% in 1990 to 81% in 2020.
“There are less and fewer coffee plantations and areas with vegetation in the city and, instead, we see more condominiums. I would attribute the decrease in May Abejón to the accelerated urbanization of the last decades,” adds the Biologist of the UCR. However, it clarifies that in rural areas this could vary, since there the loss of the habitat of the spares has not been “so drastic.”
In addition to urbanization, there are other phenomena that experts point out as possible causes of their loss, such as excessive use of pesticides (Costa Rica is the country that uses more agrochemicals per hectare, according to FAO), or variations in rainfall patterns as a result of climate change.
And although these two factors also affect Abejones, experts insist that urbanization is the first cause of their descent. “What is evident is that, in many communities, as the years go by, fewer and fewer bares of May are seen compared to those seen decades ago. Now, it would be necessary to study which species are those that have had that decrease, in what areas, in what places and how they behave. Those are questions that remain to be investigated,” says the biologist.
Many species, many prejudices
In the scientific collection of the Museum of Insects, Arias and the other three biologists that make up the team have hundreds of drawers with codes for all types of “bugs” that they store there. The scientist shows dozens of copies of bumbles of May: tiny, large, dark or golden golden color, which is clear that there is not a single Mayan abejón.
“This is a beauty,” he says while holding a copy of PHyllophaga Sanjosícola —What is that name because it is from San José, the capital of Costa Rica – and shows the tarsal nails of the insect, a key element to determine the species to which each bare belongs.
“They are really not clumsy, they are adapted to having a night flight with natural light and are very good flying in that environment,” explains Arias. The alleged awkwardness is not the only stigma charged by the bares of May. In agricultural areas, many producers consider a plague to the larvae of beetles that feed on roots because they can damage crops. “They are a very serious problem for farmers. This affects crops such as potatoes, coffee and cane,” says the biologist.
The “other face of the currency”, for Arias, is the enormous contribution of the sparkles to the ecosystem. Beetles serve as food sources for other animals, mainly for birds, but also for some mammals in tropical forests. In addition, they function as pollinators and contribute to enrichment and increase in soil fertility. “They feed on organic matter that decompose so that it can be more assimilated in the soils. In addition, their movements generate spaces on Earth that allow a greater circulation of air and water,” he says.
In the city other “fears” persist for the Abejones, especially for being supposed transmitters of pet parasites. The biologist, however, qualifies this as a myth. “A May Abejón can hardly transmit a parasite because it does not even feed on feces such as other beetles, which is where parasites that affect pets are usually found. They feed on flowers, fruits and foliage in the short three weeks of life they have abroad.”
Arias considers that, beyond prejudices, there is more and more awareness of the importance of abejones and, therefore, more people who avoid killing them in their homes. “You have to stop seeing them as a threat. In some contexts they can be pests that must be attended, but in their natural environment they are fundamental and you have to help preserve them,” he says.
