EPOW - Ecology Picture of the Week

Unusual Butterfly Lachryphagy

Unidentified Butterfly, Family Papilionidae
Seti River, Nepal

Explanation:  Standing on the banks of the Seti River in central Nepal, I happened to glance down, and saw this striking butterfly ... on my toes.  Cute.  I couldn't even feel it.

But I looked closer, and realized it was nectaring the salty sweat from my foot.  

This was an unusual, or at least unexpected, form of lacryphagy, which really means drinking (eating) tears.  That is not a very uncommon behavior of butterflies, which I have seen them do with ungulates and other species -- poised on their heads and faces, drinking tiny years from the corner of eyes.  I've also seen butterflies alight on my sweat-soaked shirt, in the tropics of central Africa and South America, and drink the sweat.  

But this was different, directly on my foot, along the edge of my sandals, and even in between my toes:

Lachryphagy is a known, studied phenomenon in butterflies (Sommung and Hawkeswood 2016), but also in bees that have been reported to drink human tears!  One study (Bänziger et al. 2009) reported over 262 cases of bees drinking human tears in Thailand, and that in some instances 5-7 bees would congregate at one eye for up to 2-1/2 minutes.  I honor the persons who sat still for that!  

Other studies report lachryphagy in moths ... such as how a moth was observed drinking tears of an antbird in the Amazon (de Lima Moraes 2018), moths drinking tears from the closed eyes of sleeping birds in Madagascar (Hilgartner et al. 2006), and a moth drinking tears from a ringed kingfisher in the neotropics (Sazima 2016).  

But mine is the first instance I've seen of butterflies attracted to toes and feet!

A look at the stark, local ground cover, however, might explain why this individual seemed so opportunistic:

  
 

Information:
     Bänziger, H., S. Boongird, P. Sukumalanand, and S. Bänziger. 2009. Bees (Hymenoptera: Apidae) that drink human tears Journal of the Kansas Entomological Society 82(2):135-150.
     de Lima Moraes, L. J. C. 2018. Please, more tears: a case of a moth feeding on antbird tears in central Amazonia. Ecology 100(2):e02518. 
     Hilgartner, R., M. Raoilison, W. Büttiker, D. C. Lees, and H. W. Krenn. 2006. Malagasy birds as hosts for eye-frequenting moths. Biology Letters 3(2):https://doi.org/10.1098/rsbl.2006.0581.
     Sazima, I. 2016. Save your tears: eye secretions of a ringed kingfisher fed upon by an erebid moth. Revista Brasileira De Ornitologia. Sociedade Brasileira De Ornitologia 23(3):392-394.
     Sommung, B., and T. Hawkeswood. 2016. A record of Cethosia cyane (Drury, 1773) (Lepidoptera: Nymphalidae) feeding on human perspiration in Thailand. Calodema 424:1-3.