Juvenile hormones and ecdysteroids (moulting hormones) are involved in insect larval growth and metamorphosis, but also in gonadal growth and reproduction. The endocrine control of reproduction in insects varies with species. In female adults of the Mediterranean field cricket, Gryllus bimaculatus (Ensifera, Gryllidae), oögenesis and vitellogenesis are accomplished by characteristic changes in hormone haemolymph titers as well as in rates of juvenile hormone III and ecdysteroid biosynthesis. Gonads and the abdominal integument are sites of ecdysteroid release in adult crickets, but also in last larval instars. Juvenile hormone III biosynthesis in the corpora allata may be controlled by allatoregulating factors, acting either neuronally or humorally. The existence of allatotropic and allatostatic peptides in the cricket brain-retrocerebral complex is proved. From the brain of adult females we isolated and identified seven neuropeptides with allatostatic activity that belong to two peptide families. Ovaries also contain a factor which suppresses juvenile hormone synthesis in vitro by the corpora allata. The possible use of insect hormones and neuropeptides in pest control is discussed.