Comment What types of bugs? (Score 1) 524
You don't state what types of bugs that you are finding.
Generally speaking, developers are good at testing functional issues - for example, if they are asked to code a "print report" function, they typically will be able to test the "print report" function so that it works as expected. What developers are poor at testing are use-case issues, where you are integrating a function within the larger scope of program. They test to make sure that the "print report" feature works, but not check to see if it handles cases where someone logs out before printing or if someone edits the data right before printing.
You have 3 choices.
1. Hire a separate tester who tests from a use-case perspective.
2. Pay for your contractors by the hour, instead of per-project.
3. Pay for a full-time employee.
As others have mentioned, developers are notoriously bad testers, especially since it sounds like that you are hiring developers for one-off jobs. A lot of development knowledge comes from working and refining the same code. Hiring one-off developers will generate more bugs than having a single person working and re-working the same code.
