Insect classic OBPs are characterized by six conserved cysteine residues. Different symbols depict OBPs from the different species at the terminal nodes: Glossina austeni (red*), Glossina brevipalpis (purple*), Glossina fuscipes fuscipes (pink*), Glossina morsitans morsitans (dark blue*), Glossina pallidipes (light orange*), Drosophila melanogaster (black*), Ceratitis capitata (sky blue*) and Musca domestica (lime green*). The symbol * represents the name of the specific OBP. Sequence alignment was performed using MuSCLE v3.8.31 and phylogeny relationship was inferred using RAxML v8 with best fitting Wheelan and Goldman (WAG) model and 1000 bootstrap iterations.