The European praying mantid, Mantis religiosa L, was introduced into North America in the late 1800s. Adults are hard to mistake for anything else, 2.5 to 3" long, brown to green (variable) and around on tall plants (golden rod, milkweed) from August until frost. I don't see any records that far west (Thunder Bay), but it is found around the Great Lakes and may have arrived by boat. You could try to reach the Great Lakes Forestry Centre in Sault Ste Marie, where they have experts who survey and identify insects. You should be aware that we have much smaller native insects (not mantids) with similarly adapted front legs. Tell your friend always to include a scale with insect photographs. That would help make a definitive identification.