Responding to Daylength
Declining day length is the central cue that triggers the monarch's migratory state. In the northern breeding range photoperiod is falling by 20 minutes this week. This sends the signal that it's time to go to Mexico.

Becoming Migratory
Watch for signs of migratory monarchs:

• flying in directional flight
• clustering in overnight roosts
• nectaring intensely

Emerging in Diapause
Beginning in mid-August in the north, adults are in diapause when they emerge from the chrysalis. They are full grown — but not reproductively mature. Their reproductive development is on pause. These monarchs will not complete development and begin to mate until next spring in Mexico.

Beginning a Long Life
The same hormone deficiency that leads to diapause also leads to increased longevity. Summer monarchs live only 2-6 weeks; migratory monarchs live up to 8 months.

Accumulating Fat
Monarchs are shifting focus now from breeding to intense feeding. They must build body fat to fuel migration and to survive the winter in Mexico.

Welcome!
Fall migration 2016 is underway. Please share your sightings and help tell the story of the monarch's long journey to Mexico.