Honeydew is a sweet and sticky liquid excreted by certain insects, usually aphids. When these insects pierce the phloem of a plant with their needle-like mouthparts, the sap—which is under pressure—shoots into the food canal of the insect, forcing the previously ingested sap out the other end. Yes, you read that right. Honeydew is fast-tracked bug poop.But it’s not that bad. Trust me. Aphids are dependent on sap for all their nutritional needs, including protein. But plant sap is mostly water and sugar with just a fraction of protein—about 1 to 2 percent of the volume. So the insect must eat large amounts of sap to get enough protein, so what comes out is very similar to what went in—minus a few amino acids. Technically, the substance cannot be called honeydew unless it’s been run through a bug’s digestive tract. Sap that just oozes from a plant is called sap.
The honeydew that is expelled lands on leaves, branches, needles, or even on the ground under the plant. This processed sap is coveted by other creatures, including ants and bees. Although honey bees prefer floral nectar, during times of dearth—especially in the late summer—they will often collect the honeydew, transport it in their honey crop, and process it just like nectar. Yum.
The liquid in honeydew evaporates quickly, so honey bees are more likely to collect it in the mornings or evenings. The bees treat the substance like nectar so it is often mixed together with the nectar from flowers. As such, it is not really noticeable in the finished honey.
Honey made almost exclusively from honeydew is known as honeydew honey, forest honey, bug honey, flea honey, or tree honey. Sometimes it is named after its primary component, such as pine honey, fir honey, oak honey, etc. It is generally dark, strongly flavored, less acidic, and less sweet than floral honey. It is prized in many parts of Europe and in New Zealand, often commanding high prices.
Not so great for bees
Oddly, honeydew honey is not considered good winter feed for bees because it can be quite high in ash, a primary cause of honey bee dysentery. Beekeepers often remove honeydew honey from their hives before the onset of winter.
The amount of honeydew in your honey depends on the plant species that live nearby, the climate, and the local weather. If floral nectar is plentiful all year long, honeydew collection will remain insignificant. In some regions, however, such as Germany and northern California, honeydew honey is quite common. Like floral honey, honeydew honey varies remarkably with its source. Its flavor, color, sweetness, consistency, nutrient content, and tendency to granulate are dependent both on the plant and the insect that collected it.
Plants that produce the sap that feeds the insects are mostly trees. Certain species of ash, basswood, beech, cedar, chestnut, elm, fir, hickory, larch, maple, oak, pine, poplar, spruce, sycamore, and willow produce honeydew, as does black locust. A few forbs produce honeydew as well, including alfalfa, cotton, currants, grapes, gooseberries, and sunflowers.