The woolly beech aphid, Phyllaphis fagi, is an introduced aphid which can be found on Fagus sylvatica. Growers report seeing them on several cultivated varieties including Fagus sylvatica'Asplenifolia', 'Fastigiata', 'Roseo-Marginata' and 'Purpurea
Pendula'.
Young aphid nymphs have been found to hatch (eclose) from overwintering eggs before bud break (Iverson and Harding, 2007). In Oregon we have had reports as early as mid-April but they become more noticeable in May. These aphids will feed and soon reach adult stages. They reproduce without mating (parthenogenesis) so populations of aphids on the spring growth can enlarge rapidly. As many as 10 generations were documented in nursery production (Iverson and Harding, 2007). Winged (alates) aphids are produced for months and winged populations peak in mid-June. No significant difference in reproductive fecundity was seen between winged and wingless females (Iverson and Harding, 2007). Winged males mate with wingless females in the fall. Those females lay eggs on stems which overwinter.
Monitor for the eggs near buds and the aphids on new growth and leaf undersides.
For information on management of aphids, check the PNW Insect Management Handbook.
Nice images can be found at Invasives.org: Woolly beech aphid
There is a discussion of woolly beach aphid at the plante doktor website.
Iversen, T. and Harding, S. (2007), Life table parameters affecting the population development of the woolly beech aphid, Phyllaphis fagi. Entomologia Experimentalis et Applicata, 123: 109–117. doi:10.1111/j.1570-7458.2007.00524.x <24 Mar 2016>
Fan-dancing woolly beech aphids - video
Orginal publication 4/20/06
Lastest revision <8 May 2017>
Author: R.L. Rosetta, Extension Nursery Integrated Pest Management, Department of Horticulture, Oregon State University/NWREC.
Woolly beech aphid and waxy ball of honeydew nearby
Colony of woolly beech aphid on leaf underside. Note honeydew near aphids.
woolly beech aphid
Woolly beech aphid eggs on twig (very small black specks).
Colony of woolly beech aphid along leaf vein. Note honeydew near aphids.
Woolly beech aphid on leaf underside near arrow.
Small woolly beech aphid near leaf hairs.
Colony of woolly beech aphid on leaf underside. Note honeydew near aphids.