Five pairs of median and 1 pair of lateral neurosecretory cell groups occur in the protocerebrum of Dysdercus koenigii, a hemipteran pest on the ladies finger plant (Hibiscus esculentus). The lateral neurosecretory cells (LNSC) become active prior to, and at the time of commencement of mating and release their secretion within 24 h of commencement. The female never mates again after laying eggs and the LNSC also never become active. It is believed that LNSC secretion induces the urge for mating in the freshly emerged female and the lateral groups of NSC form the receptivity centre in the brain.