if they sorta jump/fly and move so quick they look like they teleport and are tiny like gnats almost....
prolly an aphid of some sort
google aphid photographs and you'll find there are like 100 million or so types
they eat leaves or suck juice or butt rape the plant or something
point is they're BAD - a few prolly not, but i'd nip it OUT of the bud
neem oil is good for most bugs i think - also garlic oil, clove oil, cayenne pepper, black pepper...
when using extracts and oils, i set the plant outside of the direct footprint of my HPS for a few days
if i don't see the problem for a bit(day or 3) i like to spray the plant till it drips starting at the very top, going in circles to the bottom with hydrogen peroxide in water - it's great for the plant in just about every way - don't use the 3% - and don't mix too strong