Outer spore envelope proteins of pathogenic bacteria often present specific virulence factors and tools to evade the defence system of their hosts. Brevibacillus laterosporus, a pathogen of invertebrates and an antimicrobial-producing species, is characterised by a unique spore coat and canoe-shaped parasporal body (SC-CSPB) complex surrounding the core spore. In the present study, we identified and characterised major proteins of the SC-CSPB complex of B. laterosporus, and we investigated their entomopathogenic role. Employing a proteomic approach and a B. laterosporus-house fly study model, we found four highly conserved proteins (ExsC, CHRD, CpbA and CpbB) that function as insect virulence factors. CpbA was associated with a significantly higher mortality of flies and greater relative gene expression levels during sporulation, compared to the other SC-CSPB proteins. Taken together, we suggest that spore surface proteins are a part of a complex set of toxins and virulence factors that B. laterosporus employs in its pathogenicity against flies.