Gypsy moth caterpillars on my Colorado spruce shrubs

(Question)

My lovely Colorado spruce shrubs in our yard seem to be heavily infested with gypsy moth caterpillars. They’re eating the soft young needles and have damaged this spring’s new growth. We planted the shrubs 5 years ago and this is the first year we’re seeing caterpillars. We live in the Beach neighborhood of Toronto (sandy soil); the shrubs are east-facing and get full sun, with a bit of wind as we’re on a hill. They have always been very healthy.
I treated them with Safer’s BTK, but am wondering if there is anything else I should do. What caterpillars I can see feed day and night. How should I best protect my lovely blue spruces? Will lots of watering at root-level and fertilizing help them recover?

(Answer)

 

This topic has previously been researched by Toronto Master Gardeners.  Excellent information can be found at:

Spring is Here; So Are Tree Pests

Hope this helps.

For even more useful information go to:

http://extension.umass.edu/landscape/fact-sheets/gypsy-moth

and

http://msue.anr.msu.edu/news/gypsy_moth_caterpillars_damaging_spruce_trees