Fruit flies (Drosophila melanogaster). Each female can lay more than 100 eggs per day and give 900 successors. You won’t easy get rid of them. They grow from egg to fly in about 11 days. Fruit flies are not harmful to humans, animals or plants. There is only one natural enemy, the ichneumon wasps.

Eat (or clear away) (over) ripe fruit. Do not leave empty wine glasses, bottles etc. Or use it as a trap. In syrup or honey they stick. Create a trap with a jar with a cloth, rotten fruit in it, and a hole in the tissue so that they can get in (and not out).
They do not like fragrant herbs like lavender, dill, sage, basil and garlic.

What do you get when you give a firefly viagra? A fluorescent tube.

Would a fly without wings be called a walk? (Georges Carlin)