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Phylloxeridae : Phylloxerini : Phylloxera caryaecaulis


Phylloxera caryaecaulis

Hickory leaf stem gall aphid

On this page: Identification & Distribution Other aphids on the same host

Identification & Distribution

The eggs of Phylloxera caryaecaulis on hickory (Carya spp.) hatch in spring. Feeding by the newly-hatched immature fundatrices induces galls on young twigs, on petioles, or at bases of leaflet main veins, sometimes in clusters. The galls (see first picture below) are globular, pale yellowish green tinted with red before opening, but afterwards becoming leathery and black, and with a diameter of 5-25 mm. The adult fundatrix in the gall (see second picture below) is of a plump egg-shaped form, narrower posteriorly, dirty yellow in colour with dark legs and antennae.

Note: The identification to species is still problematic for Phylloxera species, especially those on Carya. Blackman & Eastop in Aphids on Worlds Plants note there is still no key available to differentiate alatae, the only key being one to galls (Pergande, 1904).

Images above by permission, copyright Claude Pilon, all rights reserved.

On reaching maturity the fundatrix reproduces parthenogenetically depositing up to a thousand eggs in the gall. The young nymphs that hatch from the eggs are white, shining and somewhat hyaline with pellucid white legs. More mature immatures with wing buds (see first picture below of nymphs in gall) are light yellow or yellowish green with dusky legs and antennae. These mature to alate sexuparae (see second picture below). The alatae have dusky wings, apparently distinctive dorsal prothoracic markings and a pair of orange or blackish spots on the abdomen. The body length of adult sexuparae is 0.8-1.8 mm. Small alatae produce mostly males, larger ones mostly sexual-females. After mating the females lay the overwintering eggs on hickory.

Images above by permission, copyright Claude Pilon, all rights reserved.

Phylloxera caryaecaulis has been recorded on pignut hickory (Carya glabra) and (from these observations) shagbark hickory (Carya ovata). There is no host alternation in this species of Phylloxera. It is found in eastern USA and Canada.


Other aphids on the same host

Phylloxera caryaecaulis has been recorded from 1 or 2 species of hickory (Carya glabra, Carya ovata).


We are especially grateful to Claude Pilon for pictures of Phylloxera caryaecaulis (for more of her excellent pictures see and).

Identification of specimens photographed by Claude Pilon was confirmed by Eric Maw by microscopic examination and DNA analysis of preserved specimens. For taxonomic details we have used the keys and species accounts of Fitch (1854)(1855) and Pergande (1904) together with information from Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors and those listed in the reference sections as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

Useful weblinks


  • Fitch, A. (1854)(1855). Report of the noxius, beneficial and other insects of the state of New York. Transactions of the New York State Agricultural Society 14, 859.

  • Pergande, T. (1904). North American Phylloxerinae affecting Hickoria (Carya) and other trees. Proceedings Davenport Academy of Science 9, 185-271. Full text