Heterozygous pic^GE28589 mutant adults are more sensitive to fungal infection (B. bassiana) than wild type controls. This increase in sensitivity is seen following both natural infection and infection through septic injury. No reduction in survival is seen following wounding or in response to infection with either Gram-negative (Ecc-15) or Gram-positive (M. luteus or S. aureus) bacteria. Hemocyte number in pic^GE28589/+ mutant flies is similar to wild type and hemocyte uptake of B. bassiana fungal spores appears normal, as does phagocytic uptake of S. aureus and E. coli. The number of plasmatocytes in heterozygous pic^GE28589 third instar larvae is similar to wild type, but a reduction is seen in the number of crystal cells. Less melanisation occurs following injury compared to wild type.