Milkweed, the Asclepias genus, is the only food of the monarch butterfly caterpillar. Without it, monarchs would die before ever reaching their winter hibernation areas in the mountain forests of Michoacán.
The problem: most of the natural habitat for native milkweed is being eliminated in Texas and across the United States. Even more problematic is the replacement species for many home landscapes — tropical milkweed — can play host to a deadly monarch parasite and the potential for pesticide contamination.
Tropical milkweed (Asclepias curassavica), although very attractive with its bright orange and yellow flowers, seldom goes dormant in our South Texas climate. The result is possible year-round monarch breeding that leads to increased likelihood of infection by a protozoan parasite known as Ophryocystis elektroscirrha (OE).
If a monarch lays eggs on a tropical milkweed in the fall, there is a good chance the larvae will become infected by OE. To prevent this from happening, create your own early frost by cutting back all tropical milkweed to four inches above the ground by Thanksgiving, and again on Martin Luther King Jr. Day.
Follow these tips for sustainable monarch profusion:
Let’s get out there and help the monarch butterflies. And let’s do it with common sense and science.
Butterflies in Bluemist
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About our expert
Mark A. Peterson is a conservation project coordinator for San Antonio Water System. With over 30 years of experience as an urban forester and arborist, Mark is probably the only person you know who actually prunes trees for fun. When not expounding on the benefits of trees and limited lawns, you’re likely to find him hiking San Antonio’s wilderness parks or expounding on the virtues of geography and history to his friends.
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