Do I have to pay an employee who quit without notice for days worked previously?
As a result, I had to restructure the entire season and I had to finish myself some of the work he was allotted to do. He has cost me a lot of time. Am I obligated to pay him for the last three shifts he worked?
Employees are entitled to be paid for all hours worked at the rate agreed upon. If you fail to pay him, he can obtain assistance from the Department of Labor to enforce his claim.
An argument might be made if you had a written contract with him to complete a specific project or task that he failed to do; but even in that instance, he might make a good case that he should be paid for the effort he expended in your employ.
For seasonal workers, sometimes it's a good idea to offer a lower wage with the commitment of a sizable bonus upon them completing the season. That "carrot" might help you to keep the workers you need for the time you need to have them on board.