This particular milkweed has been the focal point of some recent controversy, so I thought I would put together as much research as I could find on this Monarch favorite.
Definition – Ophryocystis elektroscirrha (OE) is a protozoan parasite that infects Monarch and Queen butterflies.
Karen Oberhauser indicates that in Southern and Costal States + California – that OE can be a problem as the plants don’t die and OE can build up. Some sites advise to cut it down to the ground at the end of the season if you are in one of the warmer climates.
Thanks to Andy S. with this article from SciencMag.org. It again talks about the Southern State problem with OE and what can be done.
Here’s a recent TedTalk which seems to indicate that Curassaivica is good for Monarchs and is in fact medicinal against OE.
I emailed Chip Taylor, a well known expert in this field, about this video and this is his response.
Here is a AskNature Article with the same information as the video.
Cardenolides per Species – interesting that Curassaivica has a very high percentage.
- Asclepias curassavica – 1055
- Asclepias syriaca – 50
- Asclepias incarnata – 14
- Asclepias tuberosa – 3
- Asclepias verticillata – 1
San Antonio note – I got this email from a woman who lives in San Antonio. She said, “Monarchs are staying at the A. currasavica milkweed patch on the San Antonio Riverwalk all winter.” If you also look at the map below, you will see a lot of Monarchs do seem to stay in the southern states over the winter. Curassavica does seem to be stopping these Monarchs from migrating.
My summation – it always makes sense to be aware of the OE problem and if in the South or California to take measures to limit use of Asclepias curassavica or at least cut it back a couple times a year. While only 8% of migrating Monarchs have OE, 85 % of the non-migrating Florida population have it.