Wax glands, wax production and the functional significance of wax use in three aphid species (Homoptera: Aphididae)

The structural details of wax glands and the physical form of the secreted wax is described for the apterae of three aphid species-beech woolly aphid, spruce root aphid and woolly apple aphid. The glands are composed of greatly enlarged epidermal cells underlying a modified cuticle that forms distinctive wax gland plates. Secreted wax in the form of threads passes out of the cuticle as filaments, the arrangement of these filaments in the cuticle above each epidermal cell gives rise to the distinctive wax skein found in each species-hollow, solid or honeycombed. It is suggested that the primary role of the secreted wax is to prevent the aphids becoming contaminated by their own secreted honeydew and that of other members of the colony. Other secondary roles considered include: individual microclimate isolation; protection from fungi, parasites and predators; waterproofing and frost protection.