Hemolymph proteins in the locust, Locusta migratoria migratorioides infected with the fungus Metarhizium anisopliae var acridum were analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Under conditions that allowed locusts to thermoregulate, 2 proteins, ITB1 (ca. 18kDa) and ITB2 (ca. 13kDa) were induced 48h post inoculation. In contrast, under non-thermoregulating conditions, only 1 band, INTB1 (ca. 18kDa) was induced with similar molecular mass to ITB1. ITB1 and ITB2 were N-terminally sequenced but showed little homology to known proteins. The induction of hemolymphal proteins in infected, thermoregulating locusts and implication in insect immune defence are discussed.