What is this growing on my arborvitae? Is it good or bad? My trees have lots of them.

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  • Doesn't look like its growing, looks like a dead tuft of leaves, is it loose, can it be lifted off? but what's that white cottony deposit at the base? Is that present at the base on all the other trees with these dead looking tufts? – Bamboo May 20 '16 at 12:29
  • It's attached, but can be pulled/twisted off. I might have actually seen one of these hanging from underneath my deck, which to me means that some sort of bug is using the leaves to make some sort of cocoon? – user1146334 May 20 '16 at 16:08
  • Pick the white fluff off and examine it closely, in case its juniper scale or some other type of invader, especially if all the dead bits you've seen have this white deposit at the base. Assuming it is a fluffy deposit and not some sort of mould. – Bamboo May 20 '16 at 16:40

This is Bagworm. Some seasons they really infest arborvitae. I don't know where you live, but I saw them quite a lot when I lived in NJ. Get rid of them as soon as possible, before they start to hatch (May/ June).

You can just cut off the nests that you can reach, directly into a plastic bag (a double layer of recycled grocery bags would do). Make sure that the bags are really sealed off before disposal, so that the moths don't hatch and spread. You may want to look into spraying, or other options for the ones in the trees that you can't reach.

Here's a link to start you on your research- https://uconnladybug.wordpress.com/tag/arborvitae/

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