This one is on an envelope because it was hard to see on anything else. These little things showed up (maybe by chance?) around the same time I had a new fence installed (pine of some sort).
They range greatly in size from 1mm to 4 or 5mm. They have six red legs and two tiny red spikes on their rear. They meander, crawling around slowly and randomly as if they have nothing at all to worry about, on everything from my fence to my patio chairs and table to the side of my house. They don’t seem to do anything at all but wander.
My biggest issue with them is that they are delicate, and any attempt to swipe them off of something usually results in their death and a small red stain on your hand or towel. They don’t hide or run, and sitting on them can force a change of pants lest you wish to have red dots all over your rear.
Their noticeable numbers in my back yard went from a few to hundreds overnight, and they were of all different sizes. There were several dozens of them on each of my patio chairs and a hundred or more on my fence. After dousing everything in my backyard with a high pressure stream of water their numbers have dropped considerably, though they have not gone away.
You have aphids in your yard. They suck juices out of plants and it sounds like you have a nice infestation on several plants. Yes they are a pest.
Aphids can be black, red, yellow, or green.
You did the best thing to control them…spraying with a jet of water. You can also spray your plants with insecticidal soap, besides keeping up with more spraying of the water.
They will die with a frost…if that is any consolation. 🙂