One of my Dad's favorite jokes was, "What's the only thing worse than biting into an apple and finding a worm? Biting into an apple and finding half a worm!"
You should (a) put the package and any remaining dates in something secure like a ziplock bag, (b) inform the manager of the store where you purchased them. This may, or may not, be something that will have to be reported to the government for further inspection and possible import restrictions - the store manager should know what to do.
It could turn out that the worms, and their larva, that infest dates are not a threat to Canadian crops and therefore all you need to do is just make sure you pit and inspect them before you eat them.
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain