Heat works on wasps and bees too..be thankful you dont have those in your truck instead of stink bugs,at least they wont sting you while your going 65 down the highway!...
I had a lot of wasps in my van thats not on the road the past few years,they built nests in the door jambs and under it,in the engine bay,etc...one day I got stung multiple times when I took the air cleaner lid off so I could spray some starting fluid in the carb,the dam wasps had the whole thing clogged with paper and there was probably 200 of them lying in wait to get me...I used the ether to douse most of them,then took out my bic lighter and napalmed them,but several got away fast enough to sting the crap out of my arm....I sprayed all the nests I found with wasp killer,but the dam things return and built next to the other nest the following year...
I found by spraying the nests,any that escaped go into the van and try escaping by buzzing against the windows...and once the sun beats on the van long enough and it gets up to 120 degrees in there,they dry up and get crispy and die--I found about 100 lying on the dash one hot day...
Worst things to eradicate are those bugs that like flour,some kind of black beetles...as a joke a guy I know dumped some flour in a co-workers defroster vents,hoping it'd blow all over him when he turned the blower on...it did,but some of the flour stayed trapped in the ducts or heater box,now the truck is infested with a million of those beetles,and you cant even sit in it when spring comes!...he's tried "boming" it several times,but those things just seem immune to insecticide...