Antistrophus gillettei

Aulax gillettei

Aylax gillettei

Cynipidae

Antistrophus

Silphium laciniatum

Alabama

Arkansas

Colorado

Illinois

Indiana

Iowa

Kansas

Kentucky

Louisiana

Michigan

Minnesota

Mississippi

Missouri

Nebraska

New Mexico

New York

North Dakota

Ohio

Oklahoma

Pennsylvania

South Dakota

Tennessee

Texas

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Wisconsin

Ontario

Cynipid galls of the eastern United States

Antistrophus minor

Antistrophus minor n. sp. 

Bred from the same stem of Silphium as the preceding species (editor: Anitstrophus rufus) and about half as numerous.

Descriptions of new Cynipidae in the Collection of the Illinois State Laboratory of Natural History

Aylax gillettei

Antistrophus minor
Aulax gillettei

Gall. Same as in A. rufus. [Desc for A rufus: In the stems of rosin weeds (Silphium laciniatum, Silphium perfoliatum, Silphium integrifolium and Silphium terebinthinaceum). There is not the slightest indication of a swelling upon the outer part of the stem and the larvae live in small oval cells in the pith of the plants.]

This species was bred by Prof. C. P. Gillette from the same stems of Silphium containing A. rufus. Two types of minor are before me and I regard this species to be nothing more than small specimens of A. rufus with ill-defined parapsidal and median grooves. The types are in the Illinois State Laboratory of Natural History. The name A. minor is preoccupied by a European species.


The North American Species of Aylax and Their Galls

Antistrophus minor

Silphium laciniatum
Cells hidden in stem [shares its description and photo with A rufus]

[Photo caption]
347. On Silphium laciniatum. Adults emerged May 15- June 24.

[Tooker and Hanks list Antistrophus rufus and minor emerging in numbers from both Silphium laciniatum and terebinthinaceum in the spring.]

Antistrophus species overwintered in dead Silphium stems and pupated in the early spring. We did not rear enough A. minor in cages to allow a reliable estimate of emergence time.

Endophytic insect communities of two prairie perennials (Asteraceae: Silphium spp.)

Gillette reared both of these species (editor: A rufus as well) from flower stalk stems of compassplant, but unlike the previous two species, there was no evidence of gall formation. Instead he found that the wasps pupated in little cells within the pith just under the outer wall of the stem. A minor was smaller and less numerous than A rufus. Dr. Gillette along with Mr. Hart visited "fields" of compassplant and "found that the majority of the stems were more or less infested with cynipidous larvae, hundreds of which could. in some cases, be found in a single stem.". They went on to investigate other Silphium species in the area and "found similar larval cells abundant in S. perfoliatum, S terebinthinaceum, and S. integrifolium". However, they did not rear specimens from these stems to see what species of Antistrophus wasps were present. 

Found wasps in stems of compassplant in Wisconsin and Iowa.

Silphium Gall Wasps: Little-Known Prairie Specialists

Antistrophus minor Gillette, 1891 

Nomenclature: Aulax Gillettei Kieffer, 1902

Feeds on: Induces galls on Silphium laciniatum L. and possibly other Silphium

Distribution: United States: Illinois

Catalog of Rose Gall, Herb Gall, and Inquiline Gall Wasps (Hymenoptera:Cynipidae) of the United States,Canada, and Mexico

Antistrophus minor
Rosinweed cryptic stem gall wasp

Hosts: compass plant (S. laciniatum)

Gall location and description: Galls of species in this group are cryptic, meaning they are not outwardly visible and can only be located upon dissection of a galled stem. When dissected, the stem will have numerous brown, oval-shaped chambers along the inside of the pith, each with a single insect. 

Range: This species group has been found throughout the Midwestern, Eastern, and South Central United States. Like many other herb galls, this complex probably occurs throughout the entire ranges of each species’ respective host plant(s). 

As with the rosinweed flower gall wasps, it was once believed that cryptic galls on rosinweeds were all induced by either of two species, Antistrophus minor and A. rufus. Recent data shows that there are multiple species of cryptic stem gall wasps on these plants, each preferring a single host plant. 

Unlike other rosinweeds, compass plant (S. laciniatum) has been found to host two distinct species of cryptic stem gall wasps. These two species are found in the same habitats, and often induce galls on the same individual host plant. The reason for this bizarre occurrence is currently unknown. 

Many unrelated groups of gall wasps seem to have indepdently developed the ability to induce cryptic, inconspicuous galls. The mechanism by which this has been made possible is not known, but it is likely that having hidden galls decreases the odds of attack by predators or parasites. Due to the known diversity of cryptic gall wasps and hidden nature of cryptic galls, it is quite likely that many cryptic galls have thus far evaded detection and await discovery!

Field Guide to the Herb and Bramble Gall Wasps of North America