Is this a Giant Mosquito?

No - it is an adult Crane Fly.

Leatherjacket larvae eventually turn into an adult Crane Fly. Leatherjackets can be a lawn insect pest in Southern Ontario.

The leatherjacket larvae feed on the crown, roots and foliage of grass plants. If there are enough of them, the damage can be severe. See Lawn Damage 

Call or email to discuss your risks and options for treatment.

For more information from the King of Green