Swarm of monarch butterflies shows up on weather radar

A swarm of monarch butterflies, winging its way south for the winter, was spotted as large blue blobs on weather radar last week.

They were seen over Illinois and Missouri before heading to Mexico. During their migration, the monarchs help pollinate a third of our fruits and vegetables.

The size of the swarm is a positive sign. Monarch butterflies have been declining at an alarming rate over the past few years from pesticides, drought, and cold temperatures along the migration route.