Eriophyes sp.
Chadwick's No. 65

Host Fagus grandifolia Ehrh.

This gall occurs on the under side of the leaves of the host plant. It is an erineum, white and frost-like at first, turning to a brown colour at a later stage. The anatomical structure of the interior of the leaf remains perfectly normal, the effect of the stimulation being confined to the epidermis. This produces a large number of unicellular, capitate hairs, resembling miniature mushrooms, the resemblance to which is the more striking since the stalks of the hairs are bulbous at the base, as shown in Fig. 3. The hairs on the normal leaf are long, acicular and unicellular. As this gall is produced with no increase in the number of cells in the leaf, anatomically it stands as a simple type of "hypertrophy", the remaining forms all exhibit the more advanced phenomenon of cell proliferation.

Acalitus ferruginea (Stebbins, 1909)

Erineum fagineum Persoon, 1822
Acalitus fagerineus (Keiger, 1959)
Acalitus ferrugineum (Farlow &Hagen, 1885)
Acalitus ferrugineus (Stebbins, 1909)

Host: Fagus grandifolia

Relationship: "Yellow erineum patches on the upper surface of the leaf: compound capitate papillae."; Erineum on leaf undersurface; "numerous granules on leaf undersurface, discolored pustules above; at first frosty, later brown."

Distribution: FL, MA, NH, PA, OH, WV

Notes: Persoon (1822) described Erineum fagineum Persoon as a fungus, producing erineum patches on leaves of Fagus sylvatica L.; thus, this name is not available as a mite name.

Hagen (1885) created the name Erineum ferrugineum P. (Farlow) (P. apparently refers to Persoon) for the mite producing erineum on leaves of Fagus grandifolia Ehrh. Farlow gave a collection of beech leaves with erinea by this mite to the Cambridge Museum; Hagen described the symptoms as "Irregular velvety rusty patches on the underside of the leaves." The mite was given the name Acalitus ferrugineum (Farlow & Hagen, 1885) by Amrine and Stasny (1994): Persoon was dropped as he had no connection with the name ferrugineum and he thought a fungus caused the symptom; Farlow was retained, since it had been used by both Hagen and Stebbins; no publication by Farlow has been found.

Stebbins (1909) listed the name Eriophyes? ferruginea Farlow as the mite producing erineum on leaves of Fagus grandifolia L. This name was not listed by Davis et al. 1982, nor by Amrine & Stasny, 1994. Stebbins was the first to assign the mite to Eriophyes (apparently derived from the name Erineum ferrugineum P. (Farlow) listed by Hagen (1885). Stebbins is thus the author of Eriophyes ferruginea producing erineum on the leaves of American Beech.

One mite forms erinea on both surfaces of the beech leaf. We found two different mites in the two different erinea (Garman suspected this in 1894, but failed to provide names); we found an Aceria in the lower surface erinea and an Acalitus in the upper surface erinea. Earlier versions of our electronic catalog listed the mite causing the lower leaf surface erineum, as Aceria ferrugineum (Stebbins, 1909) and the mite causing the upper surface erineum, as Acalitus fagerinea (Keifer), but this was wrong. Careful study has found two species of Aceria that are inquilines in the erinea on both leaf surfaces; and these can become so abundant that sometimes, only an Aceria can be recovered from an erineum.

Acalitus ferrugineum

Erineum ferrugineum Farlow & Hagen, 1885; Hagen, 1885: 26.
Aceria fagerinea Keifer, 1959a: 650.
Acalitus fagerinea; Keifer, et al., 1982: 108–109.
Acalitus fagerinea; Amrine & Stasny, 1994: 7.
Acalitus ferrugineum; Amrine & Stasny, 1994: 7.
Acalitus fagerinea; Baker, et al., 1996: 142.

Host. Fagus grandifolia (Fagaceae).

Relation to host. Erineum.

Distribution. USA, Canada