Aphids On Linden Trees (I Think) - October 2020

Back a few weeks ago, I posted some photos showing how Yellow Jackets covering our espalier'd Greenspire Linden trees due to (based on what I found line) what appeared to be aphids infesting the tree.   Recently, we had a couple of nights of frost (overnight) and that has killed away all the yellow jackets.  So, I could finally get close enough to the tree to inspect what is going on.  My assumption was that the frost likely killed off WHATEVER was eating the leaves and causing the Yellow Jackets to feast.  

But, I was pleasantly surprised when I grabbed a leaf and turned it over.  The lace-like leaf had a couple of inhabitants on the underside.  Here's what I saw:

See them?  Here's a closer look:

Two guys that are yellow and black striped and hanging out on the underside of the leaf.

But, what are they?  Pretty sure they are Linden Aphids.  The Bug Guide has a photo that sure looks a lot like these things and, ummm, they're on a Linden tree. 

But, what do I do next?  I'm not sure.  So, I emailed the Master Gardener at the University of Illinois extension office to see what they recommend.   Should I quickly spray them now - heading into Winter?  Or wait until Spring?  Hoping the Master Gardener gets back to me quickly.