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woolly ash aphid




Biological Control

Chemical Control











Aphids can have very complex biologies. They may have multiple host plants and widely varying shapes through the year. Additionally there may be confusion due to specialized terminology concerning aphid biology.

Ash trees are considered the primary host for P. americanus and noble fir trees, the secondary host. P. americanus is thought to overwinter on ash as eggs placed in bark crevices (Bugwood, 2000). The eggs hatch (eclose) in early spring and produce wingless females which reproduce without mating (parthenogenesis). This aphid form is the fundatrix or stem mother and her progeny are termed fundatrigenia, fundatripuriae, or apterous (wingless) viviparae (live birth) and also reproduce parthenogenetically. A wee bit confusing! Hang on, there's more.

The fundatrigenia give birth to winged (alate) aphids called Sexuparae. This winged stage allows the aphid to disperse, generally to the alternate host, the noble fir. This aphid form has both male and egg-laying (oviparae) female offspring. These offspring can mate and are known as Sexuales. The female Sexuales lay the overwintering eggs on the primary host, ash trees.

In the Pacific Northwest, root aphids can be found year round on both noble fir and ash trees according to nursery producers and research in Christmas tree production..



barely wooly aphid
wingless ash aphid (apterous)

waxy adult aphid
waxy adult aphid (fundatrix)

newly emerged winged aphid
newly emerged winged aphid (alate)

winged aphid (alate)
winged adult (alate)

picture of aphid feeding
note the aphid stylet or beak

root aphid stage

winged aphid


Last modified - 7/22/02


Comments or questions? Contact Robin Rosetta

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