They look like flower thrips. A search for 'thrips on snapdragons' brought up this on the internet Flower focus: Snapdragons and I copied the below from the article:

"Here in WA we are plagued by the western flower thrips and since our
farm is managed organically there isn’t a real solution to the issue.
After a few seasons of fretting about the millions of tiny dark specks
crawling all over the blooms (they love snaps) I just stopped growing
white, yellow and soft pink varieties. The thrips don’t damage the
snapdragon flowers like they do with Roses or Lisianthus but on the
light colored blooms they really stand out and attract attention. "

Even though they are not particularly damaging I'd try knocking them off with a gentle shower of water while holding the stems with one hand so they don't break. If they persist try spraying them with neem oil that you can buy at almost any garden center already mixed and ready to spray in a small spray bottle.