Southern North Island Beekeeping Group Ltd

The Giant Willow Aphid

Tuberolachnus salignus

Effect of giant willow aphid honeydew on bee honey The only sugar in willow tree sap is glucose. The honeydew secreted by giant willow aphid contains several kinds of sugar, approximately equal amounts of fructose, glucose, sucrose and a trisaccharide melezitose (Mittler, 1958 in Sopow and authors, 2017). Melezitose has low solubility and crystalizes out as the moisture content of the honey drops, creating granulated honey.

Honey affected by the presence of melezitose is often called ‘cement honey’, because it makes the extraction of commercial honey difficult. Much of the crystalline honey remains in the comb, which reduces yield.

However, there are reports in New Zealand that honey from willow honeydew is good for overwintering bees. In other counties there are reports that melezitose causes dysentery in honey bees, but observation in New Zealand indicate that the bees do not consume the melezitose crystals.

Honeydew from willow trees contains salicylic acid and may contribute to a sour taste in the honey.

Southern North Island Beekeeping Group Ltd