Apidaecins do not appear to disturb bacterial membranes, and it is not yet clear how they do work. It is speculated that these are bacteriostatic, rather than bacteriocidal, proteins. Royalisin is another antibacterial peptide is found in the royal jelly of honeybees. This is also an amphipathic protein, and its mode of action may be similar to cecropins. It is a small molecule, molecular weight estimated at 5523.
Dipterans also produce induced antibacterial proteins.
Two peptides from Phormia are called defensin and diptericin. Another dipteran peptide is a male-specific antibacterial product from Drosophila melanogaster . This peptide is known as andropin, and it thought to protect seminal fluid and the male reproductive tract against microbial infections. One of the most exciting findings in insect immunology is the discovery of an insect immune protein called hemolin. This protein belongs to the immunoglobulin superfamily, that is, it shares sequence homologies to mammalian immunoglobulins.