The best deterrant is to make sure there are no bagworm sacks left on your 'Emerald Green.' If there are any left the potential is there for next years happy family of bagworms to feast upon your prized arbs.
As for fertilzer I would not do it unless you have a soil test. Why spend money on these products and invite trouble with over application of chemicals if it is not necessary. Your county extension agent can do the test.

Dave

I found a lot on my Smaragd this summer. I spent a half hour pulling them(plant about 4'). I only had liquid sevin to spray at the time and found no others in the weeks following.

Would'nt think to waste too much money.
The arbies have feasted on fish emulsion regularly in the past.
Do bagworms just appear one day and start covering themselves with the plant matter, or are they deposited there?
Did'nt tend to them as before so much last summer (the arbs).. out of town and the lot...Also wondering if the extra cold temps this winter could eradicate the buggers.
Has anyone seen bagworms appear even during a season of regular natural spray such as this tea mixture application?

Hand picking bags now is an effective and easy control measure (if the plants aren't too tall yet!). But it is also easy to overlook a bag or two, and that's all it takes for another infestation.

In our area, bagworms hatch in late May, roughly, and can be spotted and sprayed in early June, usually. At that time they are very easy to kill, use sevin, BT, or other labelled products.

Where do they come from? That is a very good question that has never been satisfactorily answered for me. They can and do "go for walks" in their bags, but I have seen them show up in isolated beds of junipers, far from any potential batch of bags. One time a county agent made an offhand comment that he thought they might hitch a ride on birds. When I asked him later to elaborate on that, he vehemently denied any such thing...

Bottom line - a very easy pest for us to control, I wish all horticultural pests were so easy.

brian

Thanks all,
Looking alot like spring this week... guess its time for bagweed patrol and some research into the nasty alien looking predators. They will have to do thier bag hanging, bat impersonating, zombie walking existence elsewhere.
Hope they don't make it to youall's neck o' the prairie!
Tom

Bagworms are like all other caterpillars that I know of. At one point in their life cycle they can fly. So if you are in the bagworm zone you just have to learn how to deal with them. They are far less troublesome than Japanese beetles. We`ve started having them about 4-5 years ago.

So... the bagworm is a caterpiller/worm that perhaps had been deposited in egg form at some time last season?

Actually, bagworms behave a little differently than most other caterpillars. The female bagworm doesn't fly! She has deposited her zillion eggs in that bag and then went to caterpillar heaven. Those eggs will hatch out in the spring, turning into a mess o crawly caterpillar babies that you better spray with the Bt right away. Bt is effective when the insects are quite young.

Smartest thing to do, obviously, is to collect those bags now.

Here is a link that might be useful: Life cycle of bagworm.

thanks for that link on the life cycle of the bagworm rhizo. I never had researched that. At least the male flies. Live and learn!

Kudos to rizo!! Thanks will look at the link after dashing this off.