In this study the authors give immunocytochemical evidence for the presence of interleukin (IL)-1 alpha- and tumour necrosis factor (TNF) alpha-like molecules in the haemocytes of last instar larvae from the greater wax moth Galleria mellonella, Similar results are demonstrated in a continuous haemocyte line (BTI-EA-1174-A) from the salt marsh caterpillar Estigmene acraea. In Galleria mellonella larvae granular cells show a strong positive reaction with both primary antibodies, whereas plasmatocytes are stained to a lesser extent. Cell line haemocytes also react positively with both antibodies. After activating the cells with lipopolysaccharide (LPS) staining of Estigmene acraea cells is decreased, whereas Galleria mellonella haemocytes show no visible reaction in comparison to non-activated cells.