Highlights ► Cephalic secretions occur in male Oedothorax retusus spiders. ► Experimentally covered males are compared to noncovered males. ► We investigate effects of secretions on mating, oviposition and paternity. ► Secretions function as precopulatory mating effort and stimulate female fecundity. ► Females do not selectively use sperm of males with or without secretions.