Tsetse flies kept livestock farming impossible across a 10-million-km² 'tsetse belt' in sub-Saharan Africa, shaping human settlement patterns for millennia.
AgencyWHO — African TrypanosomiasisShare →
Tsetse Fly
Glossina morsitans
Reshaped the map of Africa. Gives birth to single larvae. Carries sleeping sickness.
Curated and rated by Sheriff Six-Legs and The Wild Pest field team · Six Legs Score™ (86/100, Outlaw tier) · Published Apr 25, 2026 · Updated Apr 28, 2026 · Released CC BY 4.0
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The tsetse fly transmits African sleeping sickness (trypanosomiasis), historically reshaping the geography of human settlement and agriculture across sub-Saharan Africa. Females give birth to a single fully-developed larva at a time — one offspring every 9 days. The 'tsetse belt' has kept entire regions free of cattle for millennia.
Size
8-15 mm
Lifespan
Adult 1-3 months
Range
Sub-Saharan Africa
Diet
Vertebrate blood (both sexes)
Found in
Wooded savanna, riparian forest, livestock farms
Field guide
Glossina morsitans is one of 23 tsetse fly species in sub-Saharan Africa. Both males and females feed exclusively on vertebrate blood, and several species transmit trypanosome parasites that cause African sleeping sickness in humans (Trypanosoma brucei) and nagana in cattle (T. brucei brucei, T. congolense). The disease has historically prevented livestock farming across a 10-million-square-kilometer 'tsetse belt' from Senegal to Mozambique — shaping settlement patterns, agricultural development, and political geography for thousands of years. Tsetse reproduction is bizarre: females are viviparous and produce only ONE offspring at a time. The female nourishes a single larva inside her uterus for 9 days, gives birth to a fully-developed larva that immediately pupates in soil, and produces another offspring 9 days later. Across her ~3-month adult lifespan, a female produces just 8-10 offspring total — extreme low fecundity for an insect. Sleeping sickness incidence has declined dramatically since 2000 due to coordinated WHO efforts; cases dropped from 37,000 in 1998 to under 1,000 in 2020.
5 wild facts on file
Tsetse females give birth to a single fully-developed larva at a time — one offspring every 9 days, total 8-10 in a lifetime.
AgencyRoyal Entomological SocietyShare →
Tsetse flies are viviparous — they nourish their larva internally with milk-like glandular secretions.
JournalPNAS — Attardo et al. (2008)2008Share →
Sleeping sickness cases dropped from 37,000 in 1998 to under 1,000 in 2020 — one of the largest disease-control successes of the 21st century.
AgencyWHO 2020 report2020Share →
Both male AND female tsetse flies feed exclusively on blood — most blood-feeding flies have only female blood-feeders.
EncyclopediaEncyclopedia of LifeShare →
Cultural file
The tsetse fly is one of the most consequential insects in human history. The species' role in African geography has been described in detail by John Reader's 'Africa: A Biography of the Continent' and is central to the ongoing 'Pan-African Tsetse and Trypanosomiasis Eradication Campaign' (PATTEC) led by the African Union.
Sources
AgencyWHO African TrypanosomiasisJournalAttardo et al. (2008). PNAS2008
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