In order to verify the physiological functions of male accessory gland (MAG) substances of the blowfly, Lucilia illustris Meigen, the growth and changes in metabolites of male accessory gland with aging, and the effect of male accessory gland extract on mating receptivity of L. illustris were examined. There was not a significant difference in length of MAG with aging, but the width of MAG was grown widely from 0 to 5-days old apparently. Changes in glycogen, total protein and lipid of male accessory gland substances showed same patterns but total protein content was higher than the others. Therefore, male nutrition affected the production of male accessory proteins. During the mating fed unmated male transferred larger amount of protein than that of starved male. When male accessory gland homogenates injected, mating receptivity of gravid female was greatly inhibited comparing to control, suggesting that the accessory gland substances of L. illustris alters female mating receptivity after mating.