How to get rid of them?

Looks like an adult thrip. They can be black like that, but the spikey ass in the back is the giveaway for me. Thrips have this spikey abdomen even in the larvae stage. Adult thrips lay eggs in the soft parts of the plant/leaves. Eggs hatch to larvae and the larvae literally suck the sap and sugars right out of the plants cells. ( This should leave marks on your leaves) The larvae then fall to the soil, to pupate. Once, they pupated, they hatch into adults with wings and a spikey abdomen, and crawl up to the leaves to start the process again. I haven't had much luck with soaps and neem oils because you need to saturate every part of the plant, and these guys like to hide in hard to get spots. Buy some Amblyseius cucumeris predator mites, they live soley on thrip eggs and larvae. Place these on the stems/leaves. Put Diatomaceous earth on the top layer of soil to prevent the larvae from pupating in the soil. Once you have the mites killing the larvae and eggs, and the diatoms killing the pupae, this should interrupt the cycle. Best of Luck!