Question

which insect sit on uncovered food

Answer 1

It can be mosquito or fly..

Answer 2

Generally we should never ever keep any kind of food uncovered.

There is a possibility of a number of things sitting on it.

There may be insects as well as dust accumulation on the uncovered food.

Insects such as flies, mosquitoes, mites, lizards, cockroaches, etc might sit on the food and contaminate it.