A customer brought a car in once with ants crawling all over inside & out.

We threw some ant traps in the car & left it sit for 2 days then removed them. 1 day later there were ants again, just not as many. Turned out after ripping the interior apart completely(headliner to carpet) the ants were nesting deep inside the foam of the rear seat bottom.
The car was still under factory warranty but they dont cover insect invasion unless its some Honda ants
Customer paid for almost 20hrs of labor @ $88 per hr, 2 ant traps, & a new rear seat bottom, & to have some bug people bomb it with some kind of chemical. Oh yea & an ozone shock to remove the smell of the chemicals.
I think his insurance ended up paying for it.
If the traps dont work, remove & check the seats & door panel. Then have a mobile auto detailer than can do an ozone shock come out. That should be enough to kill them & make your car smell "Clean". Ozone should be about $60 @ the cheapest.