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Species Diplazon laetatorius - Common Hover Fly Parasitoid Wasp

Braconid or Ichneumon? - Diplazon laetatorius Wasp - Diplazon laetatorius - female wasp or fly - Diplazon laetatorius - female Ichneumonid - Diplazon laetatorius - female Hover fly parasite Wasp - Diplazon laetatorius - female Diplazon laetatorius? - Diplazon laetatorius - female Wasp at porch light - Diplazon laetatorius wasp on common milkweed - Diplazon laetatorius
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)
Subfamily Diplazontinae (Hover Fly Parasitoid Wasps)
Genus Diplazon
Species laetatorius (Common Hover Fly Parasitoid Wasp)
Other Common Names
Hover fly parasite (note: this isn't actually a parasitic wasp but rather parasitoid)
Explanation of Names
Diplazon laetatorius (Fabricius, 1781)
Larvae feed on a wide variety of dipterous hosts, especially aphidophagous syrphid flies; it also attacks some Coleoptera and Lepidoptera.
Adults have been observed to feed on syrphid eggs.

I (RWC) feel certain that reports of this species parasitizing Coleoptera and Lepidoptera are erroneous. Taxacom, for example, reports whatever has been listed in literature, without regard to the scientific accuracy of the source, the rearing methods use, and so on. Of course, if the syrphid fly host instead of Diplazon laetatorius had appeared in the rearing cages (or whatever), it wouldn't have been reported as a predator or parasitoid of Coleoptera or Lepidoptera.
Life Cycle
It is thelytokous throughout most of its range and males are extremely rare.
This species likely has the greatest geographic range of any ichneumonid (and perhaps any hymenopteran) having been recorded from the Canadian Arctic to Argentina, from Norway to South Africa and Japan to New Zealand including many remote oceanic Islands. As with the subfamily, the vast majority of host records of D. laetatorius are from Syrphidae (20 genera). Its wide range is likely a result of human agriculture that has spread it along with aphids and aphidophagous syrphids. Because it parasitizes aphidophagous syrphids it can be considered a pest.
It has been reported to parasitize as many as 75% of syrphid larvae.
Print References
Townes, H. (1971). The Genera of Ichneumonidae, Part 4 (Vol. 17). Memoirs of the American Entomological Institute.(1)
Internet References
Works Cited
1.The Genera of Ichneumonidae, Part 4
Townes H. 1971. Memoirs of the American Entomological Institute, Number 17.