Question
Hello.  I have 7 Colorado Blue Spruce in our yard about 1 1/2 hours north-east of Toronto, Ontario.  The trees are approximately 6 feet tall now.

They are all being attacked by some kind of caterpillar.  They are approximately 3/4" long and are green and they eat the needles.  I have tried to find a visual match on various websites and can't seem to find any that are green.  

I've tried Safer's BTK but it's not proving too effective.  Chemical pesticides have been "outlawed" in Canada.    

Please help me save my trees.

Thank you.

Answer
Sounds like sawfly larvae not a caterpillar. BTK will kill caterpillar insects but not sawflies. Since you can not use other chemicals I would hand pick the sawflies off the small trees and destroy the insects. If you can get it spray an insecticide called Orthene and this will kill the sawflies.