The monarch butterfly is arguably the most recognizable and popular butterfly in the United States. As such, Americans have a special place in their hearts for this orange and black beauty. However, it appears that some Americans, in an attempt to help the monarch thrive, are in fact harming them.
Some gardeners, who are concerned about the health of monarch butterflies, like to plant milkweed, a plant that the monarch butterfly subsists on. This is likely in response to having heard that pesticides are destroying milkweed in agricultural fields. Since the monarch subsists on milkweed, these gardeners plant milkweed in their gardens to counteract the effects of the pesticides and to provide the monarchs with a source of food. How could that possibly be a problem?
Largely, the problem comes from the type of milkweed these people are planting— tropical milkweed. On the surface, tropical milkweed sounds like a great choice for both monarchs and gardeners: it lasts longer into the year, doesn’t have a taproot, doesn’t require replanting after being devoured or after recovering from a cold winter, and is incredibly beautiful. The problem is that tropical milkweed is not the kind of milkweed that naturally grows in these areas, and it causes major problems for the monarch.
Chiefly, it keeps the monarchs from migrating south during the winter. Normally, monarchs are motivated to fly south because the cold weather kills their food supply, so they must flock south out of necessity. Instead, with tropical milkweed in the equation, the monarchs stick around further into the fall and winter because the tropical milkweed can survive longer than the monarch expects. As a result, the monarchs stay for too long and wind up freezing to death.
In addition, tropical milkweed being prevalent in American gardens doesn’t give the monarch much motivation to search for multiple sources of milkweed, which can lead to a sedentary lifestyle that butterflies are not made for. This creates an unhealthy lifestyle for them and can even make them more vulnerable to parasites.
The end result is an environment that is dangerous for the monarch butterfly, instead of healthy. So, if you or someone you know has tropical milkweed in their garden share this information with them and suggest an alternative—it could save the lives of many monarchs.