Honey bees possess apparent orthologues for the core members of each of the four pathways implicated in immunity (Figs 1 and 2, Supplementary Material Table S1 ) and precise 1 : 1 : 1 orthology between honey bees and the flies Drosophila melanogaster and Anopheles gambiae is evident for most pathway members, especially for the intracellular components. Of the dozens of described actors in four signalling pathways predicted to play a role in insect immunity, only one protein appears to be completely absent in the bee genome: the ligand unpaired from the JAK/STAT pathway. The presence of the JAK/STAT cytokine receptor domeless and all other members of this pathway (Fig. 2) suggest that JAK/STAT remains functional in honey bees and is triggered by a currently unrecognized ligand.