SnowDrift, (are you sure? in san diego??)- welcome to Automotive Forums..
you did not mention what type of vehicle; but many mid- to upper end models
sometimes have climate ducts under the seats; so if that pyrethroid has leaked into
the plastic/ABS ducting, and dried in there, that might be the only thing that needs to
be cleaned out..
(although, again; depending upon model, Stealthee is right, as a cabin air filter can assist is minimizing air odor)
so, best product to wipe out/off any plastic duct/console side, under seat wiring harness would be tea tree oil.. pure essential oil (6-8drops) in a quart+ of water will act as an antibacterial/anti-fungal, and should deplete the chemicals from the 'bug spray'..
if this does not get rid of your odor; then it is probably soaked into the carpeting..
it this is the case, then my suggestion is to get ALL/everything off floor, take some sodium bicarbonate (baking soda) and scatter into affected area, and then a cup of water to moisten it, and let it start soaking, and after a minute or two of soaking (allowing to neutralize and vacate most of the chemical) open the car door(s) and use a pressure washer, and just a quick pressurized hit between seats and console..
(we did this when recon.-ing vehicles in houston (very high humidity), but we did not powerwash any of dash, under pedals, electronics, etc.. just a quick hit on carpet under seats (and naturally do not use power/heated seats until dried)) and then immediately shop vac water, and we would prop a box fan on seat and steering wheel; let it run, and go do lunch..
if you want, you can skip the washer, and just go at the area with a bucket water (with or without light soap), and shop vac again, and box fan; OR if no box fan, stuff newspaper in/under seat to absorb (military trick) and pull and rotate more newspaper in every 3-5min. until "mostly" dry..
i still hope it is just mostly in the abs ducts though.. i hate doing carpet; and if you do too, you could just pay the $20-40 for a car wash/detail place to do it for you..