Other Common Names
Bent-shielded besieger wasp
Synonyms and other taxonomic changes
Gnamptopelta obsidianator (Brulle, 1846)
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".
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 menechma
All have orange antennae. Presumably the spider wasp has a wicked sting, but not the ichneumon.
Includes southeatern United States
Fields with flowers, also forests
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.
Adults take nectar, apparently.
Parasitiod on Sphingid Lepidoptera larvae, especially those found on grapes, Vitis.
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.
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.)
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