It is a behavior shared by some butterflies, moths, and flies. Lachryophagy is the ingestion of tears. They obtain them from large mammals and reptiles and from some birds. They are the insects that drink tears.
Lachryophagy is supplemental feeding that seeks micronutrients. What nutrients are obtained from lachryophagy? Sodium and nitrogen, primarily, have been suggested. Tears are abundant in salt, which is where you get sodium. And also in proteins, from which some lachryophagous insects extract amino acids and nitrogen.
Reproduction and tears
Those nutrients influence the metabolic processes of the insects that consume them. For example, sodium. It is essential for cell osmosis and neuromuscular activity. Also for the absorption of amino acids in the intestine. However, the usefulness of lacriphagia goes much further.
A couple of facts connecting lacriphagia with reproduction. In most species of lacriphagia, males feed on tears. This behavior does not appear in developmental stages prior to sexual maturity. Lacryophagy is generally characteristic of sexually mature males.
Insects that drink tears derive benefits from this behavior. These include physiological improvements. They would provide males with advantageous access to females. And this would increase their chances of having offspring. However, there is another way to achieve the same result. Nutrients can be donated to the female during mating. This strategy is known as a ‘nuptial gift’. It is a parental investment aimed at maximizing your offspring and the ‘quality’ of your offspring.
Females could use this nutritious gift to produce a larger number of eggs. Also, to transfer it to the larvae. Thus, they increase their chances of survival and reach the reproductive stage earlier. The parental genes are transferred to subsequent generations.
Lachryophagy is a good example that nothing goes to waste in nature. Even an ephemeral tear can serve other organisms to survive or perpetuate itself over time.