Sunday, July 22, 2012

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:

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. more worms! proceeded to treat the host tree as 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?


  1. Flex,

    Are the inch worms a pupa form of another insect? And are they "southerners" moving north in the hot weather? My junipers seem fine but I have no RMJs, just Procumbens and Shimpaku. Are your trees handling the heat ok? My favorite little cork bark elm got really stressed and lost all its leaves. I brought it onto my porch for the shade and am keeping it watered and misted. Hate to lose this one, one of my favorites.

    Fishing has been great. How's the surfing down in Avalon?


  2. Tom...I think they change into pupae just before the moth stage. It is the moth stage which allows them to distribute eggs on other host junipers, so it is important to nail them in either the inchworm state or pupa state.
    Moths are beautiful, but so are my RMJs!

    re surf...nah...hasn't been much. But...storm season starts in a couple weeks...can't wait for some solid overhead waves!

  3. No bugs on mine! Knock on wood!