none. The serial sections obtained from the brain of Pimpla turionellae were stained with paraldehyde fuchsin technique. In this study, the density of the neurosecretory material in the median neurosecretory cells was established. The density of the neurosecretory material was observed during the oviposition period and on the 1st, 2nd, 3rd, and 4th days after oviposition. During the oviposition period, the level of the neurosecretory material in the median neurosecretory cells of insects was rather high. The density of the neurosecretory material showed a decrease after the oviposition period. The density of the neurosecretory material decreased greatly on the first day after oviposition, but this decrease slowed down or the other days.