Liposthenes glechomae (Linnaeus, 1758)

Nomenclature: Cynips Glechomae Linnaeus, 1758 | Diastrophus similis Bassett, 1881 | Aulax Latreillei Kieffer, 1898

Feeds on: Induces galls on Glechoma hederacea L.

Distribution: United States: Connecticut, Delaware, Iowa, Illinois, Indiana, Kansas, Massachusetts, Maryland, Michigan, Minnesota, Nebraska, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont

Liposthenes glechomae

Nepeta hederacea
Globular, green, fleshy, 8-11 mm in dia, turning brown in August. An introduced European species on an introduced European host plant, Nepeta hederacea, Gill-over-the-ground.

[Photo caption]

344. On ground ivy, Nepeta hederacea. Larvae transform in the fall. Adults emerged Apr 8-15 (VA); Apr 13 (MD); Apr 2-7 (VA) the next spring.

Liposthenes glechomae
Ground-ivy gall wasp

Host: Ground-ivy (Glechoma hederacea).

Gall location: Somewhat variable, usually on the leaf or petiole, but occasionally appearing on the stem.

Description: Single-chambered, spherical to amorphous galls. Usually solitary, but occasionally may appear clustered or confluent. Usually with short, pale hairs across the surface. Small and reddish when fresh to larger and greener when more mature. Old, dry galls appear brown and papery.

Range: Currently, this species has been found in Northeastern North America including many U.S. states and adjacent areas of Canada. Ground-ivy has been widely introduced and it is possible that this species will be discovered elsewhere.

This species was introduced to North America from Europe, where it is widespread and quite common. No native gall wasps are known in association with the mint family.

It has also had a tumultuous taxonomic history, and has previously been classified in many, many gall wasp genera over the centuries since its discovery by Linnaeus in 1758.

Interestingly, this species is comprised entirely of parthenogenetic females, meaning all reproduction is asexual and without the involvement of males. Parthenogenesis is known in a couple other herb gall wasps, but this type of reproduction is not unheard of in the order Hymenoptera.

Aylax glechomae

Hosts: Glechoma hederacea

Galls. — Rounded galls (Figs. 1 and 2) on the leaves, petioles, or stems of Nepeta (Glechoma) hederacea, the ground-ivy (gill-over-the-ground). Monothalamous, or several galls fused. Each gall is 6-12 mm., more or less, in diameter, rounded, covered with a rather dense, stiff pubescence, reddish and green when young; when old becoming dry, brown, smooth, with a thin, papery covering separating more or less or entirely lost from the gall during the winter. The larval cell is central, held in place by rather abundant, very irregular, coarse fibers.

Range: Europe. ME, MA, CT, NY, NJ, OH, IN, IL

Mayr first pointed out the synonymy of the European glechomae and Bassett's similis. The species was undoubtedly introduced into America from Europe, for its host, the ground-ivy, is of European origin.

The galls appear in late May or early June. In this young condition they are eaten in France. The galls mature in late July and, as the plants begin dying off in September, the dried galls drop to the ground where they overwinter, being in large part decayed by springtime. The galls are heavily parasitized. The insects mature in the fall and overwinter as adults, not emerging, however, until the following April or May. Adler proved, by experimentally raising successive generations, that there is no alternation of generations with the species and, since the male is unknown, it is likely that reproduction is purely agamic, the eggs never being fertilized.

Aylax glechomae (Linne).

Cynips glechomae
Diplolepis glechomae
Aulax glechomae
Diastrophus glechomae
Aulax glechomatis
Liposthenes glechomae
Liposthenes glechomatis
Diastrophis similis
Aulax similis

Gall. (Plate XIV, Figs. 1, 2, 3.) On the petioles, leaves and sometimes on the stems of ground ivy (Glechoma hederacea). Monothalamous when simple, polythalamous when compound. The simple galls are round, green, and covered with short hairs. When compound they are very irregular in form and size and have two or more larval cells, which are held in position by coarse fibres. When dry and old the galls are brown, with a thin paper-like outer covering, which sometimes disappears when lying on the ground through the winter and the bleached fibres surrounding the larval cells look like little burrs. Diameter, 6-25 mm.

Habitat. Europe; Massachusetts; New York; New Jersey; Connecticut; Ohio; Illinois.