Manuel Leal recently observed this A. stratulus in Puerto Rico licking a leaf high in the forest at El Verde. He describes his observation over at Chipojolab, and suggests that they are not drinking water, and that the behavior is very focused.
Recently in the Bahamas, we observed a female A. sagrei licking a leaf. It hadn’t rained in several days and there wasn’t any dew on the leaves. However, close inspection of the leaf after the leaf left indicated that it was covered with a sticky substance. Perhaps aphid honeydew?