The genus Inga contains hundreds of woody plant species in the American tropics, from tall canopy trees to diminutive understory shrubs. All species sport cup-like nectaries on their leaves, presumably an offering to ants whose presence dissuades herbivores.
Because Inga hosts a reliable entourage of happily sedentary ants, its nectaries are perhaps the easiest place in the rain forest to photograph the normally frenetic insects. Here are some recent shots from Ecuador.
(Incidentally, Linepithema tsachila is one of the species I described as part of my doctoral dissertation- always good to see an old friend!)