Sandflies

[Viz]

Sandflies & mosquitos. When there isn't any people around for them to bite, what do they eat usually?

[heathfield]

Mosquitos - nectar and fruit juices. Sandflies - plant tissues. The females of both species require protein for egg production, and since this is not present in their normal diet, they get it from the blood of animals, birds, and yes, we humans!
Ignore the males - it's the females that bite.