Fenoxycarb 0-ethyl N-(2-(4-pheoxyphenoxy)-ethyl) carbamate is the most potent juvenile hormone analogue (JHA) against a variety of insect species including the silkworm Bombyx mori. In this study, we aimed to demonstrate the effects of this juvenile hormone on major hemolymph proteins of Bombyx mori during the fifth larval instar, by using fenoxycarb and clarifying the interactions between these proteins and the juvenile hormone. Topical applications of fenoxycarb to the fifth instar larvae of Bombyx mori were performed immediately after the fourth ecdysis (on day 0) and at the beginning of the prepupal period (on day 6). Fenoxycarb application on day 0 increased the length of instar in both sexes and induced high total protein content in the hemolymph. When fenoxycarb application was performed on day 6, there was no difference in the length of larval instar and a similar total protein amount was reached with control. Detected hemolymph proteins are grouped as follows by using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE): storage proteins (72 kDa-76 kDa), 30kDa proteins, lipophorin (230 kDa), and vitellogenins (178 kDa and 42 kDa). Our results suggest that major hemolymph proteins have different sensitivities to fenoxycarb and that application days and sex are more important factors to get response.