Monarch Butterflies Struggle

Geography in the News: Monarch Butterflies Struggle – News Watch.

Near the end of February each year, scientists studying monarch butterflies at their overwintering sites in Central Mexico witness signs that the butterfly colonies were “breaking up.” This separation of tens of thousands of butterflies clustered together on single trees indicate that the populations are preparing for their lengthy spring migration from Mexico to the United States and Southern Canada. This year’s colony numbers were depressed by 59 percent and scientists are worried.

Monarchs have migrated to Mexico for thousands of years, one generation going south, and different generations heading north.  No one knows how they do it.  But we may not have the chance to study these mass migrations much longer, as the species are currently declining at an alarming rate.

One particularly disturbing conclusion is the effect of the decline in milkweed along the migration paths owing to the use of herbicides and perhaps some genetically engineered corn in U.S. agriculture. Milkweed is particularly susceptible to pre-emergent and defoliant herbicides.

Since all Monarch caterpillars live on milkweed, a decline in that species would be devastating.

How will we protect the butterflies?  What will happen if we don’t?

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