In an effort to get rid of the ants that infested my XJ while the dealer had it, they had sent the car to get detailed. This included the engine bay, where about half of the ants were found to be hiding.
So now I have a spotless engine bay. Unfortunately, the dash of New Mexico desert sand that came with my car is now gone.
Also, the someone broke a windshield trim piece while flushing out the ants. Service Advisor was a gent and came to my office to replace that (me having paid hefty diagnostic fees for another issue was definitely a factor).
I took care of the roughly 30 remaining ones last night with liquid bait, and now I think my car is finally ant-free.