Do mosquitos ever bite needlessly?

Mosquitos (females) only bite when they need blood to develop their eggs/larva. They don’t bite needlessly.

No.

Mosquitos don’t have the level of intelligence to say “I’m hungry now” or “Let’s bite @Ltryptophan just for the hell of it”.

As @kritiper said, they bite for a reason; and they’re so small and expend so much energy flying around, that they need to refill fairly frequently.

Can you imagine a meeting of the Mosquito Leadership Council deciding .. hey- let’s bite Republicans this year!!!

Mosquitoes actually start by injecting you with an anti-coagulant to keep your blood from clotting when they feed. If you feel the initial pinch and disturb them before they starting sucking by brushing them away in your sleep, they’ll fly off and start in a new spot; you’ll get multiple injections of anti-coagulant, which is what causes the itching lump.

How do you know it’s the same mosquito?
And yes as stated above, they bite only when they need blood to feed themselves.