All...Rocky Mountain junipers are very robust trees. However, down here in the Pennsylvania tropics, RMJs have a deadly pest you need to know about. This little bugger can defoliate a large percentage of your tree in several days. Of course you already know how long they take to grow back.
The pest is a type of inchworm, called "Juniper Twig Inchworm (Patelene olyzonaria)".
Here is a link to a bit of info on them:

http://www.npwrc.usgs.gov/resource/insects/cateast/pataolyz.html

I have a number of RMJs; 4 were infected with these inchworms.
Looking thru my garden, I found a landscape juniper which may be the original host tree for these pests.

The infected RMJs were isolated from  the rest, and immediately treated with Malathion.
Voila...no more worms! proceeded to treat the host tree as well...no sense in taking chances.

Spent the next few evenings removing all the dead Juniper foliage the inchworms had left.

So now in the past few days there has been no additional dead foliage appearing, and some new bits have started sprouting.

I was lucky...

Anyone else have this issue?
Flex