Got bag worms?

Sunday I noticed some brown spots on one of my evergreen shrubs (an Arborvitae). 

Upon closer inspection, here's what I found - bag worms.

Two years ago I almost lost a big evergreen in my front yard from these, so after seeing this I immediately grabbed a plastic bag and started pulling them off my 4 infested shrubs.  I'm guessing I pulled off more than a thousand.

A few of the bag worms I picked off a tree


Here's what they look like close up.  Notice they take on the appearance of a pine cone so, at first glance, you think they are part of the tree.


3 bag worms just plucked from an Arborvitae

 Its actually pretty gross pulling them off the shrub because inside each bag is a worm-like critter, and if its still in there alive, these little bags start wriggling around in your hand.  The photo below shows one of them creeping out of a bag after I had pulled it off the shrub.

Larva coming out of the bag (looks like a worm to me)

There's a reproduction cycle:  the female, while inside the bag, puts out a scent that attracts a male.  The male - from outside the bag - contributes to the fertilization process (how's that for G rated?).  The female can lay hundreds of eggs (one source says 800) in ONE BAG!!  The eggs survive winter in the bags and then become larvae in the spring

Here's the deal - you've got to pull them all of the shrub/tree and destroy them.  One article suggests burning them.  If you don't destroy them, they will crawl back to another shrub and begin feeding again.  I was careless and let some fall to the ground....and in no time at all, they had crawled right back to the same shrub.



Don't pick them off and throw them on the ground!  They'll crawl back to the shrub!

 Several sources recommend a systemic treatment of the tree to kill the bag worms.  If you don't destroy them, they turn into moths and start the whole process all over.  So check your trees!  Wear gloves if its a prickly evergreen because you've got to separate the branches and look on the inside, too!