By Rick Mikula (October 2018)
What an unbelievable Summer of butterflies! As I slowly dismantle my Monarch Migration Station I still find myself shaking my head over how many Monarchs and Black Swallowtails it has provided me. It was just truly an unbelievable joy.
Although the walls have been removed, the poly top is still in place to offer a safe haven for our migrating friends to fuel up before their long journey South. Actually, as soon as the walls were taken down other garden butterflies soon moved in to take advantage of the newly exposed blooms that had been kept just out of their reach. The milkweed and parsley had just about been eaten down to the ground and that allowed the nectar plants not only to take off, but take over, just as planned.
The beauty of the raised bed Monarch Migration Station is that you can start out fresh and clean and not risk using an old section of garden that may already have pathogens or predators waiting to sprout up and attack your caterpillars. This year I chose to use Gomphocarpus physocarpus. In the past is was called Asclepias physocarpa and it goes by a variety of common names including Balloon Plant, Goose Plant, Giant Swan Milkweed, Hairy Balls, Family Jewels, Oscar, or Cotton-bush. I wanted to try it this year because not only is it fast growing (and it is always good to experiment), but I just love the flowers and scent.
Most professional butterfly breeders use Tropical Milkweed, Asclepias curassavica because Monarchs absolutely love it. It also seems to be Monarchs first choice for egg laying. Tests have shown that females do have a preference when choosing plants for laying eggs. Their first choice is currassavica, then incarnata, syriaca tuberosa and verticillata in that order. Other tests have demonstrated that caterpillars that were fed Tropical Milkweed had the highest survival rate and the shortest time to pupation (as opposed to larvae that were fed on other varieties).
While caterpillars that were fed Butterfly Weed, Asclepias tuberosa, or Whorled Milkweed, Asclepias verticillata, had the lowest survival rate and took the longest time to reach pupation, Common Milkweed and Swamp Milkweed, Asclepias incarnata produced growth rates that were somewhere in the middle of the chart.
Although sometimes Tropical Milkweed gets a bad rap it can (at times), actually be healthy for Monarchs! Dr. Jaap de Roode, an evolutionary biologist at Emory University in Atlanta has done some very interesting studies concerning the relationship between Monarchs and various species of milkweed for their medicinal properties. Dr. De Roode and his fellow researchers created an experiment in which they raised Monarchs and bred them in the lab. When new butterflies emerged they found that some were infected with the parasites.
They then purposely mated uninfected females with infected males. The females were then placed in a cage that contained Swamp Milkweed (A. incarnata) and Tropical Milkweed (A. curassavica). What the researchers found was that the infected females laid more of their eggs on the Tropical Milkweed, while the uninfected females showed no preference for either species. Why did the infected females choose the Tropical Milkweed?
While some varieties of milkweed are more toxic than others the team concluded that the Monarch actively sought out the Tropical Milkweed to medicate their offspring. Dr. Mark Hunter at the University of Michigan Department of Ecology and Evolutionary Biology did similar test and found that it also helped Monarchs fend off the worst scourge facing Monarchs, Ophryocystis elektroscirrha. O.E. is a protozoan that shortens an adult Monarch’s lifespan, its ability to fly and reduces the number of offspring it will produce. Asclepias curassavica actually helped to reduce infections.
Can O.E. ever be eradicated in nature? First, we need to recognize a few facts.
Ophryocystis elektroscirrha is not a recent occurrence - it has been around as long as Monarchs. It is estimated that at least 1/3 of Monarchs in the US have OE to one degree or another and nearly all Monarchs in Mexico are infected with it. This parasite can be found in many countries around the world and has made its way to out of the way islands. What is most interesting is that Florida has the highest rate of O.E. in the US with Miami and Dade counties being the hardest hit. Despite being overrun with this protozoan these 3 Danaus species Monarch; D. plexippus Queens, D. gilippus and the Soldier, D. eresimus still manage to thrive. During my last visit to Florida in January of 2018 they were literally everywhere!
So, despite the fact that O.E. has been around as long as Monarchs have, it has not cause them to become extinct over the past 11,000 years. Monarchs did not start to occupy the US and Canada until after the last ice age and as milkweed followed the receding glaciers, so did the Monarch butterfly.
It seems that there have been some concerns about the use of Tropical for rearing caterpillars because of it not being indigenous to the U.S. or Canada. Northern gardeners do get somewhat of a reprieve here because it is only hardly to zone 9B. Now the Tropical worked splendidly for me in the past, but I live a safe zone where it does not overwinter. Let me reassure you that here in the Pocono Mountains, Zone 9B is a plane ride away. If you are a Southern gardener and have concerns, you may want to consider a species that is native to your state. While some experts will argue that there are between 70 to 200 species of native milkweeds in the United States the USDA feel that there are 116. While Monarch Watch claims that Monarchs only frequent about 30 varieties for use as host plants, you will still have a few local species to choose from. If you are unsure which ones can be found in your area check with your local nursery, college extension office and with their Master Gardens programs. Better yet go out and collect seeds now to use next year.
At least you’ll know that they are local!
Word of caution here. Whichever species you choose please don’t think that you are going to produce hundreds of thousands of Monarchs! You would never be able to grow enough milkweed and host plants in your MMS to produce a hundred Monarchs let alone a thousand. They are eating machines and will eat you out of house and home. Besides, that is not the purpose of the Monarch Migration Station.
The MMS was designed to help protect what you find naturally in your garden.
The concept is to plant what they need. Once you find eggs or caterpillars munching away then it is time for the walls go up and the poly roof goes on to protect your treasures. And does it ever work! My caterpillars were so healthy and active and the plants were so lush that it became a world of its own to sit back and enjoy. The plants just thrived inside the MMS and stayed pest free.
I have several patches of milkweeds consisting of a variety planted throughout my garden. Every patch became infected with aphids except for those that secured inside the MMS. They stayed healthy and strong until they were eventually consumed.
When left to their own devices many if not most Monarch caterpillars will fall prey to a wide selections of predators that include wasps, flies, and even ladybugs, but not with the MMS. Check the milkweed plants in your garden or in any field and you will surely find a multitude of hungry orange and black beetles looking for caterpillars to munch on. Now although I saw a few predators on the outside of the MMS all they could do was look and drool over an out of reach meals. Because of the MMS I only lost three caterpillars, and they were to ants. While caterpillars in the unprotected areas of my garden did not last too long and soon became lunch for hungry assassins. Ants were easily controlled by a simple little tin ant trap.
The original concept of the Monarch Migration Station was to raise and protect what you are given naturally and then open it up as a refueling station with the nectar plants that you had included in your original planting scheme. So, although I removed the walls I kept the roof on. It is to keep the plants in good shape from the many beating rain storms that most of the country have been experiencing this season. The poly roof will keep the elements from ripping up leaves or washing away nectar from the flowers.
At the beginning of this post I mentioned the inclusion of parsley into my gardening plan. That was to attract and nurture the ever beautiful, Black Swallowtail, Papilio polyxenes.
No one said that the Monarch Migration Station had to only serve Monarchs. The two small bunches of parsley that were included yielded a mass of caterpillars and many chrysalis to enjoy as an extra bonus for our efforts. And they all got along famously.
It was an unbelievable Summer of butterflies but now I can’t wait for next Spring so I can do it all over again! Thank you Monarch Migration Station.
This entry was posted on October 9, 2018.