Info sought on migrating butterflies

By Wesley Harris

One of the most popular butterflies, the monarch, is winging its way south through Louisiana for the winter. Researchers are calling on the public to report monarch butterfly sightings in eight southern states.

Scientists want to hear about sightings from December 1 to March 1 in Louisiana, Texas, Mississippi, Alabama, North and South Carolina, Georgia, and Florida. The observations should be reported at journeynorth.org.

Monarch migration is one of the greatest spectacles in the animal kingdom. In the fall, monarchs east of the Rocky Mountains migrate south to Mexico and Florida. Monarchs west of the Rockies migrate to southern California and Mexico. During the fall migration, monarchs may feed upon wildflowers in Louisiana. 

Researchers say information on sightings may help conservation efforts by determining if the butterflies can spend the winter as non-breeding adults in the southern U.S. Monarch populations have declined significantly over the past two decades. A 2016 study predicted the monarch could be extinct within 20 years.

Upon their return in spring, female monarchs search for native milkweeds to lay their eggs. However, exotic milkweeds, milkweeds treated with pesticides, and nonnative plants that seem to copy milkweeds can lead to egg deposition on a dead-end host leading to complete reproductive failure. Because monarchs live less than a year, it may take five generations of monarchs (mating, laying eggs, and developing from caterpillars) to complete a full cycle of migration.

The orange-flowering butterfly milkweed is common in north Louisiana, but land clearing and habitat destruction has eliminated many of the plants the monarch needs to survive.

With a global population of 200 to 300 million, monarchs seem secure as a species, but drastic declines and dramatically fluctuating overwintering populations have alarmed scientists. The main threats include loss of host milkweed plants, overuse of pesticides and herbicides, and loss of migratory stopover and overwintering sites.


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