Lifetime fecundity was studied in 50 females. In , I. graellsii, fecundity is a positive function of reproductive lifespan (number of days after first oviposition) and body length. First clutch size is positively related to female body length; the age has no effect. The subsequent egg clutches are positively related to the inter-clutch interval (days from last oviposition) and body length, and negatively to female age. Maximum egg production is obtained with clutches every day. Consequently, females would maximize their lifetime egg production by minimizing their interclutch intervals rather than by maximizing the size of each clutch. Since the fecundity is positively related to female size, and larval density is negatively related to adult size, there may be a density dependent regulatory process of the population size.