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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Monarchs Harmed by Storms in Mexico

This article was published originally on 3/17/2010

The monarch butterfly (Danaus plexippus) is a favorite of Iowa gardeners. The following information is reprinted from the March, 2010, Monarch Watch Update and explains the bad weather that has killed half of the monarch butterflies in their overwintering location in central Mexico. Note: Monarch Watch is a nonprofit educational outreach program based at the University of Kansas that focuses on the monarch butterfly, its habitat, and its spectacular fall migration. For more on monarch butterflies visit the Monarch Watch website (http://monarchwatch.org)  or Journey North : A global study of Wildlife Migration and Seasonal Change.
 
There has been a disaster of extraordinary proportions in the heart of the monarch overwintering area. Unprecedented rainfall from 31 January - 4 February led to flooding and landslides that resulted in the loss of many lives and the near destruction of the towns of Angangueo and Ocampo, the two municipalities that serve as hubs for those visiting the monarch colonies at Sierra Chincua and El Rosario.
 
The community of El Rosario was also hit hard with a major landslide that buried more than a dozen residents and destroyed bridges and homes. The consequences of this disaster will be felt for years by some and for a lifetime by others. Angangueo will never be the same - the one we remember before the flooding is gone.
 
The monarch colonies were also strongly impacted by the rainfall but the monarch population will recover - how long this recovery will take is a question that can't be answered at this time.
 
We have posted a series of articles about the storms in Mexico, the status of the monarch population, etc.on our blog.
 
A few quick facts:
1) An unprecedented amount of rainfall in eastern Michoacan in the first four days of February led to landslides and massive flooding in Angangueo and the surrounding area. About 50 people lost their lives in landslides and Angangueo was severely damaged. The story of the storm and the aftermath are extensively chronicled on our Blog.
 
2) A series of storms in January and February have taken a toll on the monarch population. The final estimate on the mortality suffered by the monarchs is not yet in but it is clear that over 50% of the overwintering population died as a result the harsh winter conditions.
 
3) Because of the severe mortality at the overwintering colonies, the number of monarchs returning to the breeding areas this spring will be fewer than at anytime since the colonies became known to science in 1975. These numbers are so low that they are certain to impact the number of monarchs that return to Mexico next fall.