Abstract: The primary follicles cannot grow further, and stop at N stage when adults are decapitated soou after emergence in diapausing Culex ptpiens pallens. The primary follicles begin ro develop about 24 hours after being decapitated in the 5-day old diapausing adults. Thus the role played by neuroendocrine of the head in regulation of folliaular development is conspicuous.The corpora allata (CA) of diapausing mosquitoes are characterized by their small size, little cytoplasm, no vacuole and being inactive, so there is no indication of juvenile hormone (JH).Synthesis and secretion. The primary follicles of diapausing ovary can develop when they are uansplanted into the abdomen of reproductive mosquitoes, but they fail to grow in diapauslng mosquitoes. ZR 515 (JHA) and JH extracted from haemolymph of reproductive mosquitoes can trigger diapausing follicles to develop.