dynamics of egg maturation in the parasitoid lixophaga diatraeae diptera tachinidae raised in a substitute host galleria mellonella lepidoptera pyralidae the content of the uterus and ovaries of l diatraeae an ovolarviparous tachinid fly was studied by dissecting 121 females 0 to 25 days old several size classes of flies p small m medium g big were used weighing 10 to 125 mg 125 to 135 mg and 135 to 16 mg respectively the mean number of ovarioles per ovary correlated to female size was 121 for p as against 129 for m g females the total mean number of eggs and oocytes changed with female age and weight for 0 5 10 and 15day old females this number was 56 149 158 and 202 respectively in g flies and 51 128 141 and 139 respectively in p ones to study egg maturation dynamics we counted the total number of eggs oocytes per p female y1 the eggs in the uterus y2 partially embryonated eggs y3 and entirely embryonated eggs y4 the experimental results were fitted to various age functions using a nonlinear adjustment program the models fitting each datum best were asymptotic functions of the form y a 1ekxd where a is the asymptotic value k a speed constant of the studied phenomenon and d age at the beginning of the phenomenon at emergence time each female contained a mean of 50 oocytes which passed into the uterus immediately after mating egg production continued for at least 10 days after emergence the rate of embryogenesis seemed to be influenced by the number of eggs in the uterus andor the age of the fly it was high for the first eggs then decreased progressively in our conditions the first eggs with a planidium ready to hatch appeared at 10 days postemergence to obtain a maximum number of larvae in good health it is better to dissect 12 to 18day old females the egg volume increases slightly during embryogenesis