Aulax nabali n. s.

Gall at the base of the stem of Nabalus altissimus, usually in masses surrounding stem, often extending down on main root, rarely on main fibres of root, usually about an inch under the ground, sometimes partly above the ground. Galls roughly spherical, 5 mm. -10 mm in diameter, each containing i-io cells, usually aggregated in irregular cylindrical masses of 2-14, resembling small knobby artichokes or irregular small' white potatoes. The interior of the gall has the appearance and consistence of a raw potato. They are mature about the middle of September, and retain their white appearance through winter, but in spring the colour darkens. They dry up when the interior presents the appearance of a congeries of corky, fibrous folds. The average size of 20 of the cylindrical gall masses was, diameter, 14XX; length, 22xx. The cells are small, closely confining the larva.

In the spring of 1880 a friend handed me one of these galls, and informed me he had found it on the stem of an aster. For several seasons I carefully searched our asters, but failed in finding the gall, and it was not until the spring of 1885 when I found it oil the root of Nabahis altissimus. My friend had mistaken the nude, dry stem of the nabalus for an aster.

In April, 1887, I made a collection of 33 gall masses from Nabalus altissimus growing on clay banks in open woods in St. James's Cemetery, Toronto. The galls were at the base of the stem, immediately above root. Usually the mass of galls surrounded the stem; occasionally but a few on one side. From these galls I reared 115 producers — 79 5 s, 36 ^ s, and 57 parasites, ^ s and $ s, of two species. The producers came out 1-6-87 — 9-^-^1') the parasites were a few" days later.

A collection was made from Nabalus roots growing on clay soil in open woods a iQ.\v miles north of Toronto, 20-10-88, and kept in a glass jar over winter. These galls were nearly spherical, 5X-10X dia., usually grown together in masses of 2-14, usually quite surrounding the stem, each nodule having from i-io cells. A collection of 7 1 gall masses made in Taylor's woods north of Toronto, 13-9-90, resembled artichokes or small white potatoes ; thc' interior white, about the consistency of raw potato. Each nodule con- tained from 1-3 cells; cells small, closely confining larva. These gave producers 13-5-91 — 20-5-91 ; parasites 19-5-91 — 1-6-91. $ producers were more numerous than ^ s. A collection made from several localities near Toronto from stems oi Nabahis altissimns growing on clay soil in open woods, 5-4-91, of 87 nabalus stems gathered 68 were gall bearing. The galls, as usual, a mass of rounded nodules surrounding base of stem an inch or two under ground; occasionally a few nodules on one side of stem, rarely a few nodules extend into pith canal. These gave parasites, Eurytoma, 5-5-91 ', producers first out 12-5-91 ; producers, 29 ^ s and 5 c? s ; out, 25-5-91 ; numerous parasites 9-6-91 — 25-6-91. One Eitrytoma 22-7-91. This lot of 68 gall masses containing probably 1,000 cells, gave of ptoducers 153 $s and 81 ^ s, and of parasites, of 3 species, 185 ^^s and $ s, a total of 419 specimens. When collected in the fall season these galls may be kept in moist sand in a glass jar, but the occupants seem to be hardy, and do not appear to be injured by the drying of the gall. However, it is best to collect in April or early in May. , These galls have been increasing during the last ten years, and have now probably reached a maximum. The parasites are now becoming more numerous. The producer is held to be an undescribed species of Aulax, for which I propose the name A. nabali. . The following is a description: — $. Length 2.50XX. Antennae 13 jointed, uniform brown, head and thorax black, abdomen shining brown, with a large anterior dorsal spot black ; all the tibicC, femora and tarsi brown, a little paler than the abdo- men ; wings ample, veins well defined, hyaline, irridescent at certain angles. Abdomen of ^ darker brown, and without the dark dorsal spot. From numerous specimens. I have bred from this gall numerous specimens of the Braconid Dacnusa crassitela, Prov. Provancher in his original description of this species gives Ottawa as the locality and Guignard as the collector. He does not say how the.; specimen was obtained, nor does he say anything of the ^ , which differs considerably from the 5 . I have also bred numerous specimens of the Chalcid Eurytoma aulacis, Ashm.; and I have reared two species of Coleoptera, probably accidental occupants, and many specimens of a Dipteron which Prof. Riley has kindly determined for me as of the genus Leucopis, sp. I am greatly indebted to the courtesy of Prof. Riley for this and many other identifications.

Aulacidea nabali (Brodie, 1892)

Nomenclature: Aulax nabali Brodie, 1892

Feeds on: Induces galls on Nabalus altissimus (L.) Hook

Distribution: United States: Massachusetts, New Jersey, New York; Canada: Ontario

Aulacidea nabali

Abrupt, hemispherical swellings just below surface of ground at base of plant so grouped often as to surround the stem. Has consistency of a raw potato in summer, pithy in fall.

[Photo caption]

354. On Prenanthes alba. Adults emerged the next spring June 8-11 (Chi).

Aulacidea nabali
Rattlesnake-root stem gall wasp

Host: Tall rattlesnake-root (Nabalus altissimus).

Gall location: On the lower stem or roots, often partly or entirely below where the stem meets the soil.

Description: Typically present as a large, irregular, cylindrical to amorphous cluster of smaller, round, single-chambered galls. Clusters are normally around 1 centimeter in diameter. Internally, the galls are dense and corky, and apparently have the consistency of raw potato.

Range: This gall has been reported from Ontario and throughout the Northeastern and Midwestern United States, although this species almost certainly occurs throughout more of the host plant’s range.

This gall was originally described from tall rattlesnake-root (Nabalus altissimus), but a subsequent study (Bonnie, 2010) examining organisms associated with nodding rattlesnake-root (N. crepideneus) located galls on that species as well. Lewis H. Weld also reported this gall from white rattlesnake-root (N. albus). It is unknown whether galls on the three host plants are induced by the same species, as this gall has rarely been seen in the recent past and has yet to be closely studied by this guide’s authors.

Aulacidea nabali (Brodie)

Aulax nabali BRODIE
Aulacidea nabali KIEFFER

Gall. (Plate XXVI, Figs. 1-7). At the base of the stems of Nabalus altissima, usually in masses surrounding the stem, often extending down on the main root, rarely on the main fibres of the roots, usually about an inch under the ground, sometimes partly above the ground. Polythalamous. Roughly sperical, usually aggregated in irregular cylindrical masses of 4 to 14, resembling small knotty artichokes or irregular white potatoes. The anterior of the gall has the appearance and consistence of a raw potato. When mature, in September, the gall retains its pale appearance through the winter, but in spring darkens in color. When dry the interior presents the appearance of corky fibrous folds, with numerous larval cells. Diameter 5 to 10 mm.

Habitat: Canada (Toronto); Massachusetts; New York; New Jersey.

A fine lot of galls of this species, collected at Magnolia and North Brookfield, Massachusetts, were sent to me by Miss Cora H. Clarke and Mr. Frank Dobbin. The specimens were obtained in September and October, and the adults emerged late in December.