Bassettia flavipes (Gillette, 1889), comb. nov., asexual generation

Synonyms: Neuroterus flavipes Gillette 1889: 281. Male, female and gall. Description reprinted by Gillette (1890: 21). Beutenmüller (1910: 136) suggested that this species should probably be placed in Callirhytis or Andricus rather than Neuroterus. Kinsey (1923: 136) agreed, and left this species unplaced in his revision of Neuroterus. Callirhytis flavipes (Gillette): combination by Weld (1926: 91). Melika & Abrahamson (2002: 168) considered this species should belong to Andricus, however, this transfer was made only informally, without following the ICZN requirements.

Biology. Sexual generation galls are multilocular, fleshy swellings along the leaf midrib or major lateral veins (Fig. 94) and are visible starting in mid- to late May in Edmonton. Adults emerged starting in late June or early July, and males tended to begin emerging earlier than females. Each emerging adult appeared to cut its own exit hole from the gall. Adult females of the sexual generation of B. flavipes oviposited into twig bark. We did not assess whether unmated females oviposited or produced viable eggs. Sexual generation galls have been recorded from Q. macrocarpa and Q. alba (Burks 1979, Weld 1926), and the authors additionally observed them on Q. ⨯ bebbiana (Q. alba x Q. macrocarpa) and Q. ⨯ schuettei (Q. bicolor x Q. macrocarpa) at the Jardin Botanique de Montreal in August 2007.

Distribution. USA: Illinois, Indiana, Iowa, Minnesota, North Dakota, Virginia; Canada: Alberta, Ontario (Weld 1926, Burks 1979, Ives & Wong 1988, Bergdahl 2015). Within Canada, the authors have observed galls of the sexual generation on introduced bur oaks in Alberta, and on bur oaks within their native range in Manitoba and Quebec.

Callirhytis flavipes

Smooth fusiform swelling along midrib of Q. macrocarpa in spring. Green, fleshy, polythalamous, the adults emerging about June 20.

Callirhytis flavipes

Quercus macrocarpa
Leaf galls, integral
Elongated, bare, fleshy midrib swelling in June, containing several cells.

[Photo caption (no photo)]
On Q macrocarpa. Adults were emerging July 6 when the galls were gathered (IO) Emerged June 23 (IL)

CALLIRHYTIS FLAVIPES (Gillette)

Neuroterus flavipes Gillette, Iowa Agr. Expt. Sta. Bull. 7, 1889, p. 281.

This species produces a fleshy midrib swelling on the leaves of Quercus macrocarpa in spring. Galls containing pupae were collected in Illinois at Evanston June 17, 1911, and at Winnetka June 28, 1907. Galls at Moline contained pupae June 20, 1915, and adults began to emerge June 23. From galls at Palos Park the adults had already emerged on July 2, 1917. The galls were seen also at Miller, Ind., and Brodie collected galls at Toronto. The species has previously been reported only from Ames, Iowa. The adults reared agree with paratypes in the National Museum and the species is here transferred to Callirhythis where because of the very short-pubescent, non-ciliate, hyaline-veined wings, it is related to those species bred from the flowers of oak. The forest-insect collection has flies, determined by the writer as this species, reared June 19, 1915. at Falls Church, Va., from a gall on Q. alba. [the only record of this species on this host; a dubious determination of the host perhaps?]

Neuroterus flavipes n. sp.

On bur-oak Quercus macrocarpa

Gall.--A hard woody swelling of the mid-rib or one of the main veins of a leaf, the leaf becoming much wrinkled and deformed as the result. Large galls measure three-fourths of an inch in length and one-fourth of an inch in width. The flies usually escape from the upper surface, sometimes through a slightly raised teat-like projection.

Galls were gathered at Ames, IO, July 6 1888, from which the flies had already begun to issue.