Explanation of Names
Species name likely from Latin obsidere, meaning to watch over, to besiege, to be on the lookout for. (Latin Dictionary). Suffix -nator indicates "one who", so this is the "Bent-shielded (Gnamptopelta) besieger".
Numbers
Subspecies G. obsidiantor obsidiantor, and G. obsidiantor austrina
Identification
Very large blue-black Ichneumon with orange antennae. Abdomen crescent-shaped, flattend, and strongly bent downward. Frequents flowers, presumably seeking nectar (?). Several other ichneumons have this same general pattern (Eric Eaton--comments under various photos). Eric Eaton was kind enough to ask the opinion of Bob Carlson of the USDA-SEL, who provided the identification--see photos in guide.
These large ichneumons resemble spider wasps (Pompilidae) with their beatufiful blue-black coloration and prominent orange marks. They are likely mimics of such wasps as
Entypus and
Pepsis elegans:
All have orange antennae. Presumably the spider wasp has a wicked sting, but not the ichneumon.
Range
Includes southeatern United States
Habitat
Fields with flowers, also forests
Season
Late spring-summer, into early fall in North Carolina. Brimley, p. 403, lists
Trogus obsidinator for May, June,
Trogus austrinus for May.
(1) Guide photos for North Carolina are later in the season.
Food
Adults take nectar, apparently.
Life Cycle
Parasitiod on Sphingid Lepidoptera larvae, especially those found on grapes, Vitis.
Remarks
Note that identification of species in this family is exceptionally difficult, if not impossible, from photographs, except in a few cases. Note the comments under each photo listed under this species here.
Print References
Brimley, p. 403, lists
Trogus obsidinator, T. austrinus for North Carolina. These are now apparently considered subspecies.
(1)
Sime, K. R., and D. B. Wahl. 1998. Taxonomy, mature larva and observations on the biology of Gnamptopelta obsidianator (Brullé) (Hymenoptera: Ichneumonidae, Ichneumoninae). J. Hym. Res. 7(2): 157-164. (This reference has not been seen by me, but was listed in an Internet reference.)
Internet References
North Carolina State University Entomology Collection lists the species with two subspecies from that state: G. obsidiantor obsidiantor (17 pinned), and austrina (3 pinned).
On a
list of Ichneumons from Gainesville, Florida. This gives information on hosts.
Los Angeles Natural History Museum Collection--not clear if it is found in California, or is just in the collection
