Monarchs… Absolute rulers of the Lepidopterae. They are coming. Some are already here. And… they are on their way to an isolated spot in the mountains of Central Mexico (Oaxaca) where the climate suits them in winter. Monarchs then migrate northward as far as Canada for summer. Where the climate suits them.
No one knows (yet) why this delicate creature that seems ill equipped to undertake this arduous journey of thousands of miles does this… But it does. We are still figuring out the “how” rather than the “why.” Monarchs in Australia migrate relatively short distances as do some in Florida. Monarchs west of the Rockies migrate to the southern coast of California. Monarchs living in the tropics of Mexico/South America do not migrate at all. Apparently that climate is suitable year-round.
The life span of an adult migrating Monarch is measured in perhaps 6 or 8 weeks at best. The caterpillar molts five times then pupates inside a chrysalis (cocoon). When the flying adult emerges it automatically knows whether to head north or south and the east/west direction of the preferred winter and/or summer habitats. Pretty sophisticated behavior that is somehow passed from the egg through all the metamorphic changes. The adult brain is about the size of a pinhead while the egg phase has no brain at all (yet). Add to these wonders that it takes four to five generations to complete the journey each way. In other words, the adult who flies south out of Canada never gets the “vacation” in Mexico but knows where it is.
Our local Texas Master Naturalists will be among the thousands of “citizen scientists” out there tagging Monarchs and searching for tagged Monarchs. They will be out again next spring for the journey northward. This tagging adds to our understanding every year. Now for the gardening part.
Notwithstanding all of this totally unbelievable life cycle, Monarchs will only lay their eggs and stage one caterpillars will only feed on one genus of plant we commonly call milkweeds. Not to be confused here, the term milkweed refers to any plant that contains latex (aka rubber). There are a bewildering number of other plant species that share this common name. This includes euphorbias and spurges that are abundant here in Texoma. The popular Christmas poinsettia is a euphorb that the Monarchs have no use for. It must be asclepias… Only!
Here in Texoma I have seen the most common asclepias asperula (antelope horns), asclepias viridis (green milkweed), asclepias tuberosa (butterfly weed), and asclepias incarnata (swamp milkweed or showy milkweed). There are likely a few more that I am not aware of but these four are native to our area. Many of us living in the country will have one or more of these on our property. Please learn to identify these and mow around them if they show up in areas you commonly mow.
If you live in town, these four mentioned are what you need to plant in your garden or butterfly habitat. Butterfly weed and showy milkweed both prefer sandy or gravelly well drained soils so you might have to prepare a raised area or try pot culture. Green milkweed and antelope horn can grow in heavier clay-based soils. Antelope horn (a. asperula) is the most common milkweed in our local area.
As the plight of the Monarch has been compromised by habitat loss and the use of herbicides and pesticides, it has become increasingly important for us regular folk to step in and help. These plants are becoming more available in the trade as seed or transplants. Seek them out.
Unfortunately, the asclepias that is most common in the trade is an annual variety that must be replanted every year (wouldn’t you know it). Asclepias curassavica aka tropical milkweed, bloodflower, or butterfly weed, has become controversial as far as using this plant out of its native range. It is known to carry a butterfly parasite and most butterfly experts now say not to plant it. I suppose it is better than nothing if that is all you can find locally but I do agree that local natives are always the best.
In doing my research this morning, I came across quite a bit more amazing facts concerning the migration(s). For instance, scientists have transplanted some eastern Monarchs over to the western side of the Rockies and they somehow went right to the West Coast wintering sites. Maybe they were just following the crowd? Blending in with the locals? Who knows?…
Do some research on your own or perhaps join our Rolling Plains Texas Master Naturalists for a tagging session. They generally do this at Lake Arrowhead State Park. You will learn plenty and get to know some dedicated local folks. I have always considered myself a “naturalist” but still working on mastering it. Come see us!!