The service published its decision in the Federal Register on Monday. The designation takes effect June 5.
The number of acres is smaller than the 1,933 acres proposed in 2010, but the service says the land holds enough habitat to support recovery of the species.
Service biologist Bob Harms says the land includes saline wetlands along Little Salt Creek, Rock Creek, Oak Creek and Haines Branch Creek in Lancaster County.
Several areas already have been protected through governmental partnerships. In 2013 the total estimated population of the beetles was 365.