I had the same problem with my pepper plants a few years ago, A good dusting with pulverized limestone will help aleviate them.
They are aphids. 50% rubbing alcohol & water will work, repeat often as necessary & get undersides of leaf. Also, a concoction of three hot peppers, 4or5 pods of garlic in a blender with 2 cups or so of water. Strain & mix 3 tbls./qt. water: add a couple tbls. of liquid soap for a sticker and spray. Also, just 3 tbls. clear (any color) dishwashing liquid soap in 1 qt water. will kill just about any bug through suffocation xcept fleas & ticks which carry an air bubble. If my understanding is correct. Dont over do any of these. Dont want to kill beneficial insects,birds,spiders,giecos,etc..