Do butterflies drink the tears of turtles?

Did you know that butterflies sometimes drink the tears of turtles?

This is a behaviour known as lachryphagy, meaning “to feed on tears,” and is done not only by butterflies, but by other insects such as bees and moths as well. Turtles produce tears in order to remove excess sodium from their bodies. This mineral is needed by butterflies, and unlike carnivores, they cannot obtain it from the consumption of meat. Instead, they carry out supplementary feeding on the tears of other animals, including turtles and other reptiles, in order to get the nutrients they need. Aside from sodium, it has been suggested that butterflies may also take up amino acids during lachryphagy.

In fact, butterflies often carry out a behaviour known as mud-puddling, in which they visit mud, blood, or even faeces on the forest floor in order to take up salts and amino acids. It has been shown in studies that male butterflies carry out mud-puddling and lachryphagy more often than females, as the intake of sodium increases their reproductive fitness. Sodium is also needed for flight, which males do more actively as they carry out courtship displays to secure mates.

The phenomenon of butterfly lachryphagy on turtles has mostly been seen occurring with freshwater turtles in the Amazon rainforest. It could be an example of a commensalistic relationship, in which one party benefits and the other neither benefits nor loses. This would be the case if the tear-feeding does not cause the turtles any pain, and does not transmit any ocular diseases. The butterflies are light enough that their landing on the turtles’ heads does not disturb them, and the turtles do not appear bothered when the butterflies drink their tears with their proboscises.

However, studies of moth lachryphagy on humans found that while certain species’ proboscises do not cause any pain, there are others with spiny proboscises that can cause pain and discomfort. It is also possible that butterflies may transmit ocular diseases to turtles, due to having previously landed on contaminated surfaces during their mud-puddling activities. In this case, it would be a parasitic relationship, as the butterfly gains to the detriment of the turtle. As studies on lachryphagy have mostly been done with other animal groups, it is difficult to determine whether their findings also apply to turtles, and therefore whether the relationship between turtles and lachryphagous butterflies is commensalistic or parasitic.

Lachryphagy is a fascinating evolutionary adaptation by insects to get the nutrients they require. It is remarkable to see how unlikely organisms can be interlinked, such as turtles and butterflies, and serves as a reminder that all organisms should be protected, as there are bound to be others that rely upon them to thrive.

References:

1. Main, D. (2013) A far cry from normal: Amazonian butterflies drink turtle tears. NBC News. Retrieved 27 July 2023. Link.
2. Mitra, C., Reynoso, E., Davidowitz, G., & Papaj, D. (2016). Effects of sodium puddling on male mating success, courtship and flight in a swallowtail butterfly. Animal Behaviour, 114, 203–210. https://doi.org/https://doi.org/10.1016/j.anbehav.2016.01.028
3. Moraes, L. (2018). Please, more tears: a case of a moth feeding on antbird tears in central Amazonia. Ecology. https://doi.org/10.1002/ecy.2518
4. Plotkin, D., & Goddard, J. (2013). Blood, sweat, and tears: a review of the hematophagous, sudophagous, and lachryphagous Lepidoptera. Journal of vector ecology : journal of the Society for Vector Ecology, 38(2), 289–294. https://doi.org/10.1111/j.1948-7134.2013.12042.x
5. Raloff, J. (2014) These insects thirst for tears. Science News Explores. Retrieved 27 July 2023. Link.
6. Two Julia Butterflies (Dryas iulia) drinking the tears of turtles in Ecuador. (2014) Digital photograph. Retrieved 2 August 2023. Link.