The honeydew comes from the sap of plants just like nectar, but while this is secreted through an active process, the honeydew is produced after the intervention of parasitic insects that suck the sap of plants. The plants involved in the production of honeydew, in our geographical areas are mainly conifers (fir, spruce, pine, larch), but also deciduous trees (oak, beech, poplar) and nectar trees (linden, willow, maple, chestnut, black locust, fruit trees). Even some herbaceous cultivated and wild plants can house in honeydew-producing insects (medical herb, sunflower).
The insects that allow the honeydew production are many and mostly belonging to the groups: psyllids, scale insects, aphids and leafhoppers. The production of honeydew, for quantity and emission times, is susceptible of variations even more nectar and is not constant from one year to another.