You could try spraying the pugs down with lemon water (equal parts lemon juice and water or full throttle lemon juice) it works on keeping mosquitos at bay and it might work on "chiggers"
I know it works on fleas

I do, in a heavy year of mosquitos, spray the boys down b4 they go out and it
does work, they don't come back in with any bites that drive them crazy!
As long as you can put up with slightly sticky lemony pugs, it might be worth a try at
this point!