When one lands on their neighbour they catch it, alive and intact, before it bites and then hand it over to researchers.
This is one small stage in a painstakingly slow process of research into the local mosquito population, led by scientists at Imperial College, London.
They hope that one day Burkina Faso will be the testbed for a technology that many hope will lead to the eradication of malaria, the mosquito-borne disease that is the biggest killer of children under five in Africa.
The researchers have developed a genetically-modified mosquito in their laboratory that can kill off its own species by spreading a faulty gene.
If it works in the wild, the technology – called gene drive – could help eliminate malaria where decades of efforts involving bed nets, repellents and insecticides have failed.