Looks like aphids to me, at least green ones. Not sure what the black winged ones are. May be they feed on aphids? I would rake and dispose the leaves - either burn them or bring to city compost pile(if you have one), high temperature compost should kill them. Home compost doesn’t get hot enough.
OK, just confirmed, black one are aphids too
They multiply by hours… You may not have a chance to catch them. What is strange, is the fact they appear in fall. They usually multiply like that in spring. Not sure how your weather is, but here many plants think it is spring - we had couple frosts and now it is a week around 70 and soil is wet after some rains - perfect spring condition.I saw a rhododendron flower today…
It has been in the 70s overcast and rainy for 3 or 4 days. Not typical November weather for sure. Yes they have multiplied quickly and across species. I’m worried that I will be leaving them in the grass even after raking.
Some will definitely stay there, but to burn what you could is better then nothing. You may mow the grass and dispose it in plastic bags in trash. But most likely the ants already save the “mothers” for next year, so real battle will be in spring. Spraying ground will not help you much… To kill aphids you really have spray it directly - they are slow and wouldn’t come in contact with insecticide unless they are directly exposed. In the early spring make tangle foot collars around the trees - it really helps if you make sure there is no other way up for the ants . Just do it while ants are still sleeping.
I did it on my cherries around beginning of April(zone 6), but you can do it anytime when tangle foot is workable. Just do not apply directly to the bark, I used plastic food wrap, then tangle foot. It is interesting, how nothing can help when ants bring them up. I had aphids on cherries every year and almost had no new grows because of them. Then I saw a lot of lady bugs and their larva on the trees, but NOT where the aphids are. I started to read about it and found that ants actually protect the aphids. Then I applied tangle foot right in the middle of the summer with all the aphids still on the trees. In 2 weeks they were gone - tangle foot will not stop lady bugs and other good insects that eat aphids, they have wings.
My recommendation instead of spraying for aphids at this point is to just let them go and try to bring in plants conducive to ladybugs to control them. They are a nuisance but ladybugs will take out the whole population in short order. See “The Grouchy Ladybug” by Eric Carle for reference.