We do not see bagworms either, but perhaps either twig blights were present in a prior year, or environmental stress (drought or staying too wet, for example) caused some needle loss. We noticed a depression in the second photo, which looks almost like a tree or large shrub was taken out. If that is the case, was that plant shading or crowding those juniper branches? Sun-loving evergreens like juniper will shed needles over time from branches getting too much shade or which are cramped against a neighboring plant (or structure like a solid fence or wall). Once gone, those needles do not regrow. You can trim off any bare branches for aesthetics, but unfortunately nothing will get the plants to replace any lost branches at this point.

Miri