Mesostenus thoracicus

Cresson, 1864

Mesostenus thoracicus is a of ichneumon in the Ichneumonidae. The Mesostenus comprises approximately ten species in North America north of Mexico, with bold black, white, and red coloration typical of the group. Members of this genus are that target caterpillars, particularly those in the families Pyralidae, Crambidae, and Tortricidae. Females possess a long, tail-like ovipositor used to deposit in insects, while males lack this structure.

Mesostenus thoracicus by (c) Annika Lindqvist, some rights reserved (CC BY), uploaded by Annika Lindqvist. Used under a CC-BY license.Mesostenus thoracicus by (c) Sam Kieschnick, some rights reserved (CC BY), uploaded by Sam Kieschnick. Used under a CC-BY license.Mesostenus thoracicus by (c) skitterbug, some rights reserved (CC BY), uploaded by skitterbug. Used under a CC-BY license.

Pronunciation

How to pronounce Mesostenus thoracicus: /mɛˈsɒstɛnəs θoʊˈræsɪkəs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Females can be distinguished from males by the presence of a long, tail-like ovipositor. The is boldly marked in black, white, and red. Body length ranges approximately 6-13 mm. The ovipositor is often mistaken for a stinger by observers, but is non-venomous and used solely for -laying.

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Distribution

North America. Specific distribution records include Edmonton and Aweme in Canada.

Host Associations

Behavior

have been observed visiting sunflowers (Helianthus spp.) to feed on extrafloral nectar. They persistently return to nectar sources despite interference from ants that also seek the sweet secretions.

Ecological Role

Mesostenus function as agents, parasitizing caterpillars of several . They help regulate of agricultural and stored product pests including the Indianmeal Moth and sunflower pests.

Human Relevance

Has potential value in of stored product pests and agricultural pests. The long ovipositor of females is frequently mistaken for a dangerous stinger, causing unnecessary alarm.

Similar Taxa

  • Other Mesostenus speciesTen occur in North America north of Mexico; identification to species level requires expert examination. M. sicarius is closely associated with Opuntia cacti.
  • Other ichneumon wasps with long ovipositorsMany in Ichneumonidae have females with prominent ovipositors; Mesostenus is distinguished by its bold black, white, and red coloration and small size (6-13 mm).

Misconceptions

The female's long ovipositor is commonly mistaken for a stinger, leading to fear of these harmless . The ovipositor is not venomous and cannot sting humans.

More Details

Taxonomic note

Described by Cresson in 1864. The Mesostenus is nearly worldwide in distribution.

Research opportunity

associations are known for only a few Mesostenus ; rearing caterpillars may yield new host records for M. thoracicus specifically.

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Sources and further reading