The seasonal migration of animals over hundreds or thousands of miles is one of the great wonders of nature that never fails to inspire. Migrating hummingbirds and geese make extraordinary trips every year. How they find their way and then have the ability to survive the long trips is nothing short of amazing.
Monarch butterflies are one of these incredible animals that make annual migrations in the fall from as far north as Canada to overwinter grounds in Mexico (and California for those west of the Rockies). The discovery in 1975 of the overwintering grounds in the high mountainous forests of Mexico was a great event, and enabled researchers to better study and understand the biology of this beautiful and amazing insect. Millions upon millions of monarchs crowd every available space from top to bottom of the native conifers that characterize this very small area in Mexico. Loss of habitat in the mountainous area where they overwinter has been an ongoing concern, with poachers logging the important trees where they spend the winter, and efforts are ongoing to ensure these sites are preserved and protected.
Since the early 1990s, the overwintering population of monarchs in Mexico has been steadily declining, as measured by total area occupied by the monarchs each winter. It has dropped from a high of about 21 hectares to a record low (since records have been kept starting in 1994) to 0.67 hectares this winter. That is alarming and cause for concern.
It is estimated that 29 to 33 percent of the monarch breeding range in the U.S. and Canada has been lost due to agricultural practices, land development and use of herbicides to control weeds along rights-of-way and in production agriculture, all reducing stands of milkweed species, which are the only host plant on which the monarch butterflies lay eggs.
The drought in Texas and southern U.S. and other weather conditions are also thought to have negatively impacted their population.
Since milkweed is so important to the reproduction and survival of monarchs, scientists have been making a plea for folks to include some in their gardens, landscapes and also in areas where they could multiply and large colonies could be established.
There are several varieties of milkweed, or butterfly weed, which are very attractive and make great additions to the flower garden. They bloom over a long period during the summer, and they serve as host to the monarch butterfly larvae that eats up the foliage. So, plant several together in a mass. You’ll create a better visual floral impact that way, and won’t have the predicament of a single plant getting eaten up by monarch larvae.
Milkweeds have a milky sap that includes toxins that are stored in the larvae and adult monarch, making them distasteful to potential predators.
Tropical Milkweed (also called Blood Flower) is Asclepias curassavica. For our region this is an annual plant that easily comes up from seed every spring if the soil is not heavily mulched. It grows about 3 feet tall, topped with clusters of bright yellow and orange flowers.
Simply known as Butterfly Weed, Asclepias tuberosa is a long-lived native perennial that can be found in well-drained soils along highway right of ways, fields and fence lines. It emerges from a tap root every spring, and is topped with showing bright orange flowers that attract not only monarchs, but a host of other butterflies that sip on the flower’s nectar.
Swamp milkweed (A. incarnate) is another native perennial milkweed found on moist soils in Texas and southeastern United States. It bears clusters of light purple flowers.
A couple of other native milkweed varieties that are less showy and frequent fields and rangeland in Texas are Asclepias asperula (Antelope Horns), and A. oenotheroides (Zizotes Milkweed), which is found mostly in Central and West Texas, although it has been reported in the sandy soils of Marion County here in East Texas.
Growing Asclepias from seed can be a little challenging. Tropical Milkweed is pretty easy, and requires no pretreatment. Other species benefit from a chilling treatment, placing them in moist potting soil in the refrigerator or between damp paper towels in plastic bag, and chilled for several weeks. After treatment, they need warm soils to germinate. Transplant in late spring after the soil has warmed.
The monarchwatch.org website, a program of the University of Kansas, is dedicated to the conservation of the monarch butterfly, and has a world of information on monarchs. They also sponsor the Monarch Waystation program, which encourages folks to establish gardens featuring milkweeds and other flowers to support migrating monarch butterflies. There is a Monarch Waystation in the IDEA Garden. More recently, Monarch Watch has created a program selling milkweed plants and listing some nurseries for each region of the United States that sells Asclepias seed or plants.
Dr. Chip Taylor of KU is the founder and director of Monarch Watch. He ends his latest blog post, which details the current status and low monarch population, with this admonition:
“Looking ahead, NOAA is predicting higher than normal temperatures for Texas in March and April — which wouldn’t be good. On the other hand, some of the weather services are projecting normal temperatures through mid-March. That sounds better to me. Let’s hope there are favorable conditions for monarchs over the next several years. While waiting for conditions to improve, let’s plant milkweed — lots and lots of it.”
Keith Hansen is Smith County horticulturist with the Texas A&M AgriLife Extension Service. His web page is http://EastTexasGardening.tamu.edu. His blog is http://agrilife.org/etg.