The neurohormone ovary ecdysteroidogenic hormone I (OEH I), originally identified from Aedes aegypti (L.), has an effect on mosquito ecdysteroidogenesis. Would there be a similar presence and function in other adult flies, e.g., black blow fly, Phormia regina (Meigen)? One pair of median neurosecretory cells (MNC_{OEH I}) and one pair of lateral neurosecretory cells (LNC_{OEH I}) were immunopositive to OEH I antiserum in the brain of sugar-fed and liver-fed female P. regina. In addition, two pairs of neurosecretory cells (SOGNC_{OEH I}) positive to this antiserum were found in the suboesophageal ganglion only in adult female P. regina at 16, 20, 23, 28, 36, and 72 h after a liver meal. In addition to the positive pairs of MNC_{OEH I} and LNC_{OEH I} in females, there were four more pairs of positive neurons (MSNFNC_{OEH I}) in the region between the MNC_{OEH I} and the esophageal foramen in P. regina males, but not in females. The presence of OEH I in male flies needs further attention as to the function of this hormone in male dipterans. We also found substances positive to Drosophila melanogaster Meigen insulin receptor antiserum located in the corpus cardiacum and the nerves going to the corpus allatum of adult female P. regina at 6 and 30 h after the liver meal, but not to the brain.