it might work,, i don't know
when i was a kid i bought a special muffler for my lawnmower that had a fitting in it to screw in a metal bottle of bug stuff
i would mow folks yards and kill the mosquitoes in the process,,, smoke all over hell's half acre

that stuff worked pretty good, damn near killed me too
however not sure if the citronella would be effective after actually being burned in combustion...
who know's might be worth a try... or fit the exhaust with a drip tube?
bob g