Butterflies cause fascination for many people. Passionate about traveling the world to watch them (butterfly watching) and there are clubs (mainly in the USA and England), identification books, species list and festivals related activity. There are also those who believe that these little winged creatures can do their chance to disappear landing on you. However, this simple act is so full of ulterior motives. What to us is a sign of good luck for insects is a matter of survival. Nectar is the primary energy source of the butterflies, but this sugary liquid produced by the flowers, does not contain all substances necessary for the life of these animals. Minerals are essential for reproduction of butterflies, especially for males in need of specific nutrients for the production of spermatophore (a kind of capsule that contains the sperm). They will do anything to get pass their genes to the next generation. Aside from gathering in large groups around small puddles, the male butterfly seek other sources of nutrients, including urine, feces and sweat. Thus, a butterfly that lands on us wants minerals contained in drops of sweat we produce. She's just thinking about playing. You can take advantage of this behavior to attract the insects and watch them more closely. You can mount a "restaurant butterfly" putting a bit of saliva on the fingertip. It takes patience, and does not work with all the butterflies, but increases the chance your luck change for the better.