Larvae of this fly breed and feed on onion bulbs underground, but generally not enough to decimate the harvest.
* MAP NOTES: The territorial heat map above showcases (in red) the states and territories of North America where the Black Onion Fly may be found (but is not limited to). This sort of data is useful when attempting to see concentrations of particular species across the continent as well as revealing possible migratory patterns over a species' given lifespan. Some insects are naturally confined by environment, weather, mating habits, food resources and the like while others see widespread expansion across most, or all, of North America. States/Territories shown above are a general indicator of areas inhabited by the Black Onion Fly. Insects generally go where they please, typically driven by diet, environmental changes, and / or mating habits.