Hi,
There is a myriad of free online resources based on horticultural research from various institutions on a variety of gardening topics. One such resource out of IA lists the many reasons Junipers turn brown https://hortnews.extension.iastate.edu/2002/5-10-2002/brownjuniper.html
This resource sheet states that “Fungal tip blights, cankers, mechanical damage, and salt injury are some of the most common causes.” It goes on to discuss some management techniques depending on each reason.

You asked whether it could be Scale? There is a great photo of Scale damage in an Extension Fact Sheet from of the University of MN. The photo does not appear to resemble anything similar to what you have described https://apps.extension.umn.edu/garden/diagnose/plant/evergreen/juniper/needlesbrowntip.html

You also mentioned a concern about needle drop. Advice from the Colorado Extension weekly Blog on this topic http://csuhort.blogspot.com/2019/08/when-to-worry-about-evergreen-needle.html explains "It is typical for all evergreen trees to shed out old needles in the fall. Fall needle drop is usually preceded by yellowing of old (often interior) needles. Sometimes needle drop happens in early summer, especially if a tree has been recently transplanted. Trees can lose up to 90% of their roots when transplanted, which seriously hampers the tree’s ability to provide its needles with vital water and nutrients. Therefore it is common in the first few years after transplant for a new tree to have needles that turn yellow or brown weeks or even months before they typically do in fall.
Premature needle drop in newly transplanted evergreen trees is especially common in interior needles. Evergreen needles often turn a pale sickly shade of green during transplant shock. Once needles discolor, they never recover their original dark green or blue hues. Instead, the tree will retain the weakened discolored needles for several years until the tree has put on enough new healthy growth that it no longer requires the old weak needles for photosynthesis. At this point, the old interior needles will turn yellow or brown and soon after drop off. In spruces and pines, interior needle shed is common August – November. In these instances, summer needle shed is not usually cause for concern."

Could not pull up the files you suggested - perhaps outdated?

I'm not sure why this won't open for you. I'll try again, but if clicking on it doesn't work, then cut and paste it into your browser. It is an article from the Minnesota Extension about Junipers so not everything in it will apply to Denver, however it gives a good overview with good photos of common problems that occur with Junipers:

https://apps.extension.umn.edu/garden/diagnose/plant/evergreen/juniper/needlesbrowntip.html

If this doesn't work, send us multiple photos of your junipers that clearly show the entire plant and close-ups of the damage and the black bugs. Without identifying the problem, we can't recommend a management control or strategy.