Antistrophus silphii

Antistrophus laciniatus

Antistrophus rufus

Antistrophus minor

Antistrophus bicolor

Gillettte described this species as forming abrupt, large (2.5-4.5 cm) subglobular swellings at the tips of the stems of rosinweed and cup-plant. Each gall supported may wasp larvae.

Reported discovery of A silphii galls in Wisconsin.

Gillette described this species as forming individual small (4-5mm), egg-shaped galls occurring in clusters in the flower disks of compassplant. Each gall supports on wasp. The galls occupy the center of the flower disk among the male (sterile) florets. The flowers appear unaffected by the wasps, with the fall slcuster becoming evident only as the flower head ripens and falls apart, revealing the galls. 

Reported A laciniatus from four sites in Wisconsin.

Gillette reared both of these species (editor: A minor 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.

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.

Gillette did not offer much information about this species. He described it from single specimen from Normal, Illinois. Bothe the host plant and gall of the wasp were unknown to him. Seventy years later, Weld reports the collection date of Gillettes's type specimen as being July, 6, 1884 and the accompanying accession catalogue as stating "from Silphium integrifolium".

Silphium Gall Wasps: Little-Known Prairie Specialists