The Hessian fly or barley midge, ''Mayetiola destructor'', is a species of fly that is a significant pest of cereal crops including

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...

barley Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley p ...

and rye. Though a native of Asia, upon its discovery it was believed to have been transported into North America in the straw bedding of Hessian troops during the

American Revolution The American Revolution was an ideological and political revolution that occurred in British America between 1765 and 1791. The Americans in the Thirteen Colonies formed independent states that defeated the British in the American Revoluti ...

(1775–1783), thus the origin of its common name. However, the report of an inquiry made in 1788 by

Sir Joseph Banks Sir Joseph Banks, 1st Baronet, (19 June 1820) was an English naturalist, botanist, and patron of the natural sciences. Banks made his name on the 1766 natural-history expedition to Newfoundland and Labrador. He took part in Captain James C ...

states that "no such insect could be found to exist in Germany or any other part of Europe". Nonetheless, it appears that this species, or one exactly like it in habits, had been known for at least a century prior to the American revolution from a locality near Geneva, and also for a long time from some regions in France. There are usually two generations a year but may be up to five. In the spring the dark-coloured female lays about 250 to 300 reddish eggs on plants, usually where the stems are covered by leaves; the larvae feed on the sap and weaken the plants so that they cannot bear grain. The Hessian fly was described by

Thomas Say Thomas Say (June 27, 1787 – October 10, 1834) was an American entomologist, conchologist, and herpetologist. His studies of insects and shells, numerous contributions to scientific journals, and scientific expeditions to Florida, Georgia, the R ...

in 1817. It is a very harmful insect. It mainly attacks the stem, although if it is especially hungry it will eat any part of the plant it can find. In 1836, a severe infestation of Hessian flies resulted in a crop shortage aggravating the financial problems of farmers prior to the Panic of 1837.McGrane, Reginald Charles. (1924, 1965) The Panic of 1837: Some Financial Problems of the Jackson Era. New York: Russell & Russell Inc.

Host defense

''M. destructor'' is one of the most destructive

pests worldwide, hence its name. This has brought it much attention from wheat breeder and genetics researchers. As a result the highest number of mapped

R gene Resistance genes (R-Genes) are genes in plant genomes that convey plant disease resistance against pathogens by producing R proteins. The main class of R-genes consist of a nucleotide binding domain (NB) and a leucine rich repeat (LRR) dom ...

s for resistance to insects in wheat are R genes for this pest specifically, with the unrelated

Russian wheat aphid The Russian wheat aphid (''Diuraphis noxia'') is an aphid that can cause significant losses in cereal crops. The species was introduced to the United States in 1986 and is considered an invasive species there. This aphid is pale green and up to 2 ...

(''Diuraphis noxia'') also being of serious interest.

References

Cecidomyiinae Diptera of North America Insects described in 1817 Taxa named by Thomas Say Agricultural pest insects {{agri-stub