September is the month to look for masses of migrating monarch butterflies in Kansas.

Navigating strictly on instinct, every monarch east of the Rocky Mountains navigates toward a limited area of central Mexico to spend the winter.

Several generations separate the southward-migrating monarchs from those that went south the previous year, so they do not have elders to show them the way.

The monarchs that live north of Kansas begin moving south in late August. The trigger for their trek south is thought to be the declining angle of the sun as days get shorter, and this sun compass guides them as they travel.

As the migrating monarchs progress south, local monarchs join them, making the group larger. The observed peak for the Topeka-Kansas City area typically falls around Sept. 22.

On the right day in the right location, careful observers may see hundreds or even thousands of monarchs moving in a south-southwesterly direction on their journey to Mexico. During rest periods, tree branches may be so loaded with monarchs that branches bow and appear almost completely orange.

Monarch movement is strongly affected by prevailing weather patterns, so every year may take them on a different route. A good way to attract monarchs and help them refuel on their fall migration is to have September-blooming plants.

For more information on monarch butterflies , contact the Monarch Watch program at Kansas University online at at www.monarchwatch.org.