A method was developed for estimating initial and final density, average longevity, and average daily rate of mortality among instars of a natural population of grasshoppers. Longevity of nymphs averaged from 6.3 to 13.6 days per instar; the mortality rate averaged from 3 to 13% per day. Average longevity of adults seldom exceeded 3 weeks, the mortality rate averaged from 3.6 to 40.5% per day. Age-specific life tables are given for six common rangeland species that were monitored for 3 years.