Butterfly “mud puddling” and expelling waste fluids in the Peruvian Amazon.

Butterflies and some day-flying moths are often observed sitting on the muddy shores of stream and river banks or around the edges of ponds and lakes – particularly in the tropics. What are they doing there in the mud? These insects are targeting things that they can’t easily get elsewhere, salts, amino acids, ammonium ions, and other nutrients. The phenomenon is called “mud puddling” or “puddling” and is common, worldwide, among butterflies, some moths, and a variety of other insects. The behavior can also take place on carrion, dung, and rotting vegetation. Blood, tears, and sweat can also be directly targeted. In fact, a mixture of beer, smashed citrus, smashed banana, salt, and even urine has been used to draw in butterflies and day flying moths. Basically, water is taken in by the butterflies and salts/amino acids are stripped from the liquid. But the process can produce quite a volume of “waste liquid.” These liquids need to be expelled. Interestingly, the excess water is expelled forcefully in some species. I was able to capture the phenomenon here where this butterfly is forcefully expelling a stream of water from its vent during a mud puddling event. Photographed alongside a rainforest pool, Loreto, Peru - September 2017.