My wife loves dalhia and plants them every year. Of course, I get to water and care for them. I know nothing about them which is usually not a problem, they grow like weeds. This year we have one plant that has some nasty looking bugs. Hopefully there's a simple solution, otherwise I'm afraid the whole plant will need to go to protect the others. See the pictures below. Any tips welcome.
Here is a link that might be useful: bugs