MacRumors reports that Apple has released OS X 10.10.5 beta to the public beta testers

With only a few months until the public release of OS X 10.11 El Capitan, OS X 10.10.5 may be one of the last significant updates to Yosemite. The new beta can be downloaded from the Software Update mechanism through the Mac App Store on Macs enrolled in the Apple Beta Software Program. The pre-release software's build number is 14F6a, the same as the OS X 10.10.5 beta seeded to developers earlier this week. It also appears that the first OS X 10.10.5 beta is now showing up in Software Update for developers who were unable to see the pre-release software following its release on Tuesday.

  Apple Seeds First OS X 10.10.5 Beta to Public Beta Testers