The beet armyworm, Spodoptera exigua, injected with the bacterial endotoxin (LPS), can be induced to produce relatively high titer (approx. 1 mg lysozyme/ml) of lysozyme activity. This enzyme, like other insect lysozyme is heat stable under acid conditions and has a M(r) of 15 kDa. Infection of S. exigua by Beauveria Bassiana, disrupts the host cellular defense but does not induce lysozyme activity nor interfere with the ability of S. exigua to synthesize lysozyme in response to LPS challenge. The S. exigua humoral components induced by LPS challenge, although possessing antibacterial activity, do not have any observable effect on the in vivo development of B. bassiana.