''Therion circumflexum'' is a species of

ichneumon wasp The Ichneumonidae, also known as the ichneumon wasps, Darwin wasps, or ichneumonids, are a family of parasitoid wasps of the insect order Hymenoptera. They are one of the most diverse groups within the Hymenoptera with roughly 25,000 species cur ...

in the family

Ichneumonidae The Ichneumonidae, also known as the ichneumon wasps, Darwin wasps, or ichneumonids, are a family (biology), family of parasitoid wasps of the insect order Hymenoptera. They are one of the most diverse groups within the Hymenoptera with roughly 2 ...

Distribution

This species is widespread in large parts of the

Palearctic realm The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...

(Europe, Asia, North Africa) and also occurs in the

Nearctic realm The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface. The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America t ...

(North America).

Description

''Therion circumflexum'' can reach a body length of approximately . The head and thorax of these relatively large parasitic wasps are predominantly black. The scutellum is yellow. The abdomen is predominantly orange. Usually the rear end and the top of the third tergites are black. The female has a short spike. The legs are yellow-orange. The posterior femur and posterior tibia have a dark brown apical end. The wings are orange-hyaline. In the clypeus the median apicali tooth is missing and the hind tarsal claws are evenly curved.D & JP Balmer
Therion circumflexum (L. 1758) at Flickr
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Biology

The adult parasitoid wasps of this species fly from mid-June to September. They parasitize various moth species including small engrailed (''

Ectropis crepuscularia The engrailed and small engrailed (''Ectropis crepuscularia'') are moths of the family Geometridae found from the British Isles through central and eastern Europe to the Russian Far East and Kazakhstan. The western Mediterranean and Asia Minor ...

''), privet hawk (''

Sphinx ligustri ''Sphinx ligustri'', the privet hawk moth, is a moth found in most of the Palearctic realm. The species was first described by Carl Linnaeus in his 1758 10th edition of ''Systema Naturae''. Description It has a wingspan (generally deflexed ...

''), pine hawk-moth (''

Sphinx pinastri ''Sphinx pinastri'', the pine hawk-moth, is a moth of the family Sphingidae. It is found in Palearctic realm and sometimes the Nearctic realm. This species has been found in Scotland but is usually found in England. The species was first descri ...

''), pebble prominent ('' Notodonta ziczac'') and a number of owlet moths (''

Noctuidae The Noctuidae, commonly known as owlet moths, cutworms or armyworms, are a family of moths. They are considered the most controversial family in the superfamily Noctuoidea because many of the clades are constantly changing, along with the other f ...

''). The female wasp lays its eggs in the caterpillars. The hatched larvae feed on the caterpillar and pupates later in a thin web.Commanster
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References

Parasitic wasps Insects described in 1758 Taxa named by Carl Linnaeus {{ichneumonidae-stub