Honey Dew , a saccharine liquid found upon trees, and, when abundant, sprinkled upon the surface between them. This phenomenon has been the subject of much discussion; by some its origin is attributed to insects, and by others it is held that insects have no agency in the matter. It would appear that both parties are correct. That plant lice or aphides do excrete a saccharine liquid is a well established fact (see Aphis), of which any one by careful observation can satisfy himself. On the other hand, it seems to be equally well established that sometimes this liquid is exuded by the leaves of trees, without any insect being concerned in the operation. What causes the plant to throw off sugar in this manner, and always upon the upper surface of the leaves, is a question needing further investigation. Dry weather is most favorable to its production; it is readily washed away by rains, and has been observed to reappear upon the same tree several times in succession. The production of honey dew is especially frequent upon linden trees.

Bee-keepers regard this as of some importance as a source of honey, and ants and other insects are fond of it.