Head to head
Tsetse Fly vs Robber Fly
A tsetse fly and a robber fly are both predatory or parasitic true flies with genuinely unusual biology, though the two have evolved in almost entirely opposite directions in terms of diet and reproduction.
| Tsetse Fly | Robber Fly | |
|---|---|---|
| Scientific name | Glossina spp. | Asilidae |
| Diet | Vertebrate blood, both sexes | Other insects |
| Reproductive strategy | Live birth of a single larva | Egg-laying |
| Disease vector | Yes, African trypanosomiasis | No |
| Hunting method | Not applicable, blood feeding | Fast aerial ambush |
| Prey subduing method | Not applicable | Enzyme-injecting bite |
| Habitat | Savanna and forest | Grassland and forest |
| Conservation status | Least Concern | Least Concern |
Tsetse Fly vs Robber Fly: common questions
Do both flies feed on blood?
Only the tsetse fly feeds on blood, with both males and females requiring vertebrate blood meals throughout their adult lives, while the robber fly is a predator of other insects entirely, capturing prey through fast aerial ambush rather than blood feeding.
Why does the tsetse fly give birth instead of laying eggs?
A tsetse fly gives birth to a single fully developed larva at a time rather than laying a large number of eggs, an unusual reproductive strategy that nourishes the larva internally before birth, a rare approach among insects not shared by the robber fly, which reproduces through conventional egg-laying.
How does the robber fly overpower insects bigger than itself?
A robber fly injects captured prey with saliva containing powerful digestive enzymes that quickly immobilise and begin liquefying internal tissues, combined with a strong grip and fast, precise flight, allowing it to subdue insects considerably larger than its own body, a hunting method entirely unrelated to the tsetse fly's blood-feeding biology.