From The Mill Pond, Dorchester, Ontario:

That little blue flower that’s popping up in the lawns right now is called Scilla… and it’s bad.

It’s an invasive species that’s toxic to pets and humans if ingested
It’s a fast spreading bulb
It crowds out native spring flowers
It provides little or no nutrients to local insects

To manage it, gardeners should prevent seeding by mowing or removing flowers, and dig up bulbs (ensuring all bulbils are removed) before they spread to nearby woods