HONEYDEW. Many insects known as plant lice and scale insects secrete a sweet fluid which collects on the leaves of trees in such quantities that it sometimes falls to the ground like a fine rain. Cars parked under such a tree will have the windshield completely covered with the sticky fluid in a few hours. Plant lice or aphids are the best known producers of honeydew. They are usually small greenish insects which have a pair of tubes on the sixth segment of the abdomen from which the sweet fluid is excreted. They suck sap from the trees in enormous quantities in order to obtain sufficient proteins and minerals for growth, and in so doing obtain far more sugar than they can possibly use. This excess sugar is then discharged through these special tubes. When honey plants are scarce honeybees often collect this honeydew from such trees as elms, oaks, hickories, citrus trees, firs and pines, and store tons and tons of the fluid. Usually such honey is dark and poorly flavored and has a limited sale. Honeydew honey contains a higher percentage of ash and dextrines; it also turns a ray of polarized light to the right whereas honey from flowers turns it to the left. In some cases honeydew has a good flavor and is sold for table use as in the case of fir honeydew on the west coast. Over 400 tons of honeydew have been shipped from the Hawaiian Islands collected chiefly from the sugar-cane leaf-hopper, an insect which often causes serious loss to the sugar-cane industry.
Bark-lice (Kermes) are common on oak trees where the females resemble galls on the stem (see page 59). The females secrete great quantities of honeydew usually in the early fall. So much may be secreted that it hangs from the oak trees in streamers. This honeydew has a strong molasses flavor which is liked by some but is not usually popular.
The pine-leaf scale insects often are very abundant on the base of the pine needles. (See Figure.) There have been numerous reports of bees working on pines in the late fall in the southern Alleghenies, especially in eastern Tennessee, which are probably based on the secretions of these insects.
A surplus of honeydew is sometimes stored from com which is obtained from the secretions of the corn-leaf aphids. Beekeepers sometimes erroneously ascribe this to the corn tassels which the bees may also be visiting for pollen.
Honeydew is all right for brood rearing in the spring and summer but contains too much indigestible material to be safe for wintering. Since it has been thoroughly digested and sterilized by the bees it is a perfectly good substitute for floral honey provided the taste is not objectionable. Even in such cases it may be salable for use in baking.