Morphological changes in the reproductive organs and neuroendocrine centers of Eurysternus mexicanus Harold males and females of known age and behavior were studied in the laboratory. In females, ovarian activity was related to morphophysiological changes in neuroendocrine centers; in males, similar changes influenced glandular reservoirs during several stages: prenesting, copulation, nesting, and infanticide. In females, the activity of the pars intercerebralis and corpus allatum during prenesting is related to vitellogenesis and sexual maturity; during nesting, it is linked to oviposition and nest care. In males, both these periods are characterized by modifications in the neuroendocrine centers relating to the synthesis of accessory gland secretions that accumulate in glandular reservoirs until copulation takes place. Larvicide was committed only during provisional nest care–by 88% of females after copulation during the early days of nest care and by 66% of copulated females when brood balls had 2nd and 3rd instar larvae. Twenty-two percent of males committed larvicide before copulating with the females that were caring for provisional nests. The changes noted in neuroendocrine centers and gonads during larvicide are the same as those related to copulation. Factors that may lead to larvicide could not be determined, as its physiological regulation must be extremely complex.