Heterozygous Ge-1^GE10187 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 Ge-1^GE10187/+ mutant flies is similar to wild type and hemocyte uptake of B. bassiana fungal spores appears normal. However defects are seen in the phagocytic uptake of E. coli and S. aureus. The number of plasmatocytes in heterozygous Ge-1^GE10187 third instar larvae is similar to wild type, as is the number of crystal cells. As in wild type, strong melanisation occurs in response to injury.