First determine if it is really chinch bugs or not. Very easy to do, look for them. If not it is likely SAD (Saint Augustine Decline)

It appears to be. I checked the areas around the outer edge of the affected spots and found a large number of small bugs with a white spot on the back. I heavily treated the affected areas with bug spray and lightly treated the rest of the yard. I supposed I should follow up with a second treatment in a few weeks? I have never dethatched my yard but I have read that you cannot really do that with SA with a power rake because it'll pull out the grass. Is there a method to dethatch? Should I just aereate?