Ongoing education………..
Back in September I wrote a blog post for Smithsonian Gardens about how excited I was by the bounty of monarch Butterflies inhabiting the Mary Livingston Ripley Garden. It was so enchanting to see the quantity of Monarchs in all stages of life – there were adults flitting from flower to flower; there were lots of caterpillars happily munching away on Asclepias curassavica, a tropical milkweed that I had allowed to self-sow abundantly in the garden; and for those keen eyed enough, there were glorious jade colored Chrysalis in abundance.
It was AMAZING!! But as September changed to October, I started to get a bit nervous about those wee caterpillars and remaining chrysalis. I started checking daily to see if they were pupating and getting out of Dodge. If you remember, Monarchs do not survive here in the DC metro region during the winter. They must migrate south to Mexico. There are populations that remain at the southern tip of Florida, and warm parts of Southern California, however the populations here on the East coast start gathering in September and make the arduous journey together. But my Monarchs seemed to have no clue that they should be doing anything of the sort. They were enjoying the unseasonably warm days, and feasting on the abundance of nectar and new growth on the tropical Milkweed. I was starting to seriously worry. And my concerns were unfortunately confirmed.
Alfonso Alonso, a Monarch specialist with the National Zoo, came for a visit and shared quite a bit of information with me which made me realize how much damage a single well- meaning gardener can do.
First off, Alfonso confirmed that yes, my Monarchs were not even thinking of packing for the trip south. Rather than packing up to leave, they were settling in – Alfonso pointed out numerous small caterpillars in NOVEMBER… these guys have no chance of making the migration.
Why would they? They had a gravy train of their favorite food—apparently the tropical milkweed, Asclepias curassavica I was growing is irresistible to them, something like chocolate for me. They were not leaving as long as it was still there and flourishing. So I immediately started yanking the tropical milkweeds – and much to my surprise an adult was following me with my cart full of yanked blooming plants. I assumed she just wanted a final sip of glorious nectar – but no – SHE WAS LAYING EGGS! IN NOVEMBER!! Yikes! I really had confused her by growing the tropical milkweed.
Alfonso suggested that if I wanted to still grow the tropical milkweeds, I need to cut them back early in September to give the butterflies a reminder that it was time to pack. Sounds easy, but since they would be in full glorious bloom, it would be really hard to do. Perhaps I could bring myself to do that, but would all of my visitors have the same toughness? Would they remember when to yank it? Probably not. As a public gardener, Asclepias curassavica has moved to my DO NOT GROW list. That part of the lesson from Alfonso wasn’t so bad, but he wasn’t done yet.
Next he shared with me information about Ophryocystis elektroscirrha or OE. This is a single celled organism that is an insidious parasite for the Monarchs. OE was first described over 20 years ago and is thought to have evolved along with the Monarch. However, now that more and more Monarchs are being hand reared in large concentrations and then released to the wild, the parasite is wreaking havoc on the fragile monarch population.
Ok – here is the jist of it: OE is a protozoan parasite which begins its life cycle as an inactive spore which needs to be eaten by the caterpillar larvae. Once eaten, the spore begins to multiply and then when the caterpillar reaches the pupal stage (chrysalis) these spores are on that butterflies’ scales when it emerges. The insidious cycle continues when the spores are transferred by the adult when laying eggs or feeding on milkweed, where the spores will be consumed by new caterpillars. EEK! But what makes the tropical milkweed so nefarious is because it continues to grow in warm areas, numerous lifecycles of butterflies will feed on the same plant—the older the plant, the more time OE has had to buildup populations.
So what is so bad about the Monarch’s having this alien being growing inside of them? well, just like many diseases, a small dose will not have a major effect, however in larger doses, the caterpillar may not have the strength to pupate, or not be able to properly emerge, or even those that ‘make it out alive’ may be so weakened that they do not have the strength to make the journey to Mexico.
These are a few of the Chrysalis I harvested from the Ripley Garden, November 2. Most are showing signs of OE infection. Alfonso recommended that I collect and destroy these so that the OE spores would not continue to build up in the garden.
It is heartbreaking isn’t it? Mother Nature is a fragile thing, and we gardeners can unknowingly wreak havoc on what we hold so dear. So, going forward, my lesson learned is to continue to grow as many milkweeds as possible – but only those that know to die back in the fall so that I am not tempting anyone to stick around for the winter nor harbor nasty alien beings!
Janet Draper
Horticulturist for Mary Livingston Ripley Garden
Smithsonian Gardens
thank you so much for this warning. The milkweed I grow in southern California blooms all year. I am going to take out all my plants now and plant new ones in the spring. I hope that will help get ride of the spores.
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