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Family Ichneumonidae - Ichneumonid Wasps

Wasp - Therion morio Wasp - Banchus Ichneumon Wasp - Dusona small wasp - Gelis - female Hover fly parasite - Diplazon laetatorius - female Ichneumon Wasp - Trogus pennator Thing - Ophion - male Pimplinae? - Pimpla pedalis - female Megarhyssa sp. - Megarhyssa macrurus - female
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Hymenoptera (Ants, Bees, Wasps and Sawflies)
No Taxon ("Parasitica" - Parasitoid Wasps)
Superfamily Ichneumonoidea (Braconid and Ichneumonid Wasps)
Family Ichneumonidae (Ichneumonid Wasps)
Other Common Names
Ichneumon Wasps (note that this name may cause confusion with the genus Ichneumon so may be inadvisable to use)
Darwin Wasps (Source)
Synonyms and other taxonomic changes
The family was revised by Henry K. Townes in the 1960s and 1970s. Some of his names are no longer in use or have changed meaning, due to conflicts with the International Code of Zoological Nomenclature or to advances in taxonomy. Many earlier comments within BugGuide, and much old literature, used Townes' names & concepts, such as Gelinae (now Cryptinae) and Ephialtinae (now scattered within Pimplinae). See summary of the history of Townes' classification.

This site follows the classification of Wahl(1) and not Townes
Explanation of Names
Ichneumonidae Latreille‎, 1802‎
from the Latin ichneumon, from the Ancient Greek ἰχνεύμων ('tracker') + -idae (taxonomic family suffix)
~5,000 described spp. in almost 500 genera in the Nearctic Region, possibly 3,000 more undescribed(2); arguably, the largest animal family, with the estimated 60,000 species worldwide (up to 100,000, according to some estimates(3)).
3-40 mm
Slender, wasplike. Two recurrent veins. 2nd submarginal cell small or lacking. Base of cubital vein lacking, 1st submarginal and 1st discoidal cells fused as a discosubmarginal cell. The resulting vein structure is often noted for its "horse head" shape:

Antennae with 16 or more segments and usually at least half as long as body.
They vary greatly in size and color; many are uniformly colored, from yellowish to black and others are brightly patterned with black and brown or black and yellow; many have middle segments of antennae yellowish or whitish.
The majority resemble slender wasps but differ from the stinging wasps (Scolioidea, Vespoidea and Sphecoidea) in having longer antennae with more segments (usually at least 16). Many have long ovipositors, often longer than the body.
Ichneumonids are notoriously hard to identify: aside from the sheer number of species, there are numerous cases of distant relatives that appear almost identical. Any identification based solely on comparing images should be treated as suspect unless an expert has said there are no lookalikes for the species or group in question.

Diagram comparing recurrent vein(s) of Braconid and Ichneumonid wings (Washington State University).

Key to subfamilies and general description in(3)


Subfamily Hybrizontinae (=Paxylommatinae)

Common almost everywhere
a great variety of hosts (mostly immature stages) is used, though most species attack only a few host types; some infest spiders and other non-insect arthropods(4)(5)
Life Cycle
Many hibernate as adults, usually under loose bark of fallen trees(6)
Many species help control insect pest populations and some have been introduced for that purpose.
No common name, Bathyplectes curculionis. From the Palaearctic, 1911, to control the Hypera postica (Alfalfa Leaf Weevil)
No common name, Bathyplectes infernalis. From the Palaearctic to control Donus zoilus (Clover Leaf Weevil)
No common name, Collyria coxator. From the Palaearctic, to control Cephidae Cephus pygmaeus, Janus integer
No common name, Eriborus terebrans. From the Palaearctic, from 1927 through 1940, to control Ostrinia nubilalis (European Corn Borer)
No common name, Exenterus amictorius. From Europe, to control Diprion similis (Introduced Pine Sawfly)
No common name, Lemophagus curtus. From the Palaearctic, 1969 and 1971, to control Oulema melanopus (Cereal Leaf Beetle)
No common name, Mesoleius tenthredinis. From the Palaearctic, to control Pristiphora erichsonii (Larch Sawfly)
No common name, Neotypus nobilitator. From the Palaearctic to control (?)
No common name, Olesicampe benefactor. From Europe, to control Pristiphora erichsonii (Larch Sawfly)
No common name, Phaeogenes nigridens. From the Palaearctic, to control Ostrinia nubilalis (European Corn Borer)
No common name, Phobocampe unicincta. From the Palaearctic, to control Lymantria dispar (gypsy moth)
No common name, Pimpla instigator. Probably from W Palaearctic, to control Lymantria dispar (gypsy moth)
No common name, Pimpla turionellae. From the Palaearctic, to control Cydia pomonella (Codling Moth)
No common name, Pleolophus basizonus. From the Palaearctic, to control Neodiprion sawflies
No common name, Temelucha interruptor. From the Palaearctic, to control Rhyacionia buoliana (European Pine Shoot Moth)

A few minor subfamilies(3) are not yet in the Guide:
Diacritinae (Holarctic; 3 genera worldwide, 2 spp. in 2 genera in NA)
Microleptinae (Holarctic; a single genus represented in NA by 2 spp.)
Phrudinae (worldwide except Australian; 13 genera worldwide, 4 represented in NA by 6 spp.)
Stilbopinae (Eurasia and the Americas; 24 spp. in 3 genera worldwide; represented in NA by Stilbops latibasis) (Townes 1989 Revision can be found here.)

Large ichneumonids (eg. Ophioninae & Netelia spp.) can sting in defense, although they may not be able to inject venom like the Aculeata. Small ichneumonid stings can't penetrate human skin.