''Chaetorellia acrolophi'' is a species of tephritid fruit fly known as the knapweed peacock fly. It is used as an agent of

biological pest control Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or ot ...

against noxious knapweeds, especially spotted knapweed (''Centaurea maculosa''). The adult fly is light greenish brown with brown-banded wings and iridescent green eyes. It is 3 to 5 millimeters lon
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The female lays about 70 eggs beneath the

bracts In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also loo ...

on immature

flower heads A pseudanthium (; : pseudanthia) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, composite flowers ...

. When the

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

emerges from the egg a few days later it burrows into the flower head and feeds on the developing florets. As the larva grows it begins to feed on the developing seeds, often consuming the entire contents of the flower head during its two-week larval stage. It

pupa A pupa (; : pupae) is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages th ...

tes inside the empty flower head. This fly is native to Europe. It was first released as a knapweed biocontrol in the 1990s in

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

, and it is currently established in much of the western United States. It is host-specific to invasive knapweeds, preferring spotted knapweed, and has not been known to attack any native plants. The fly is often outcompeted by other species that attack knapweed flower heads, such as certain weevils, so it does best where there are no competitors.

Distribution

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

, East to

Belarus Belarus, officially the Republic of Belarus, is a landlocked country in Eastern Europe. It is bordered by Russia to the east and northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Belarus spans an a ...

Turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...

. Introduced to

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

References

External links

Cornell Biocontrol Profile
Tephritinae Insects used for control of invasive plants Insects described in 1989 Diptera of Europe Diptera of North America {{Tephritinae-stub