Honeyvine Milkweed (Cyanchum leave)

Honeyvine (swallow-wort) doesn't look like a milkweed with its heart-shaped leaves and creepIng vine.  (It belongs to a different genus than the other milkweed species). I wasn't sure why it was selected to be in the research plot, and, because it can be invasive, I certainly didn't cheer for it to do well.  However, all 6 plants survived, and it did sustain a number of monarch larvae.  In my research plot, there were 12 monarch throughout the summer on honeyvine; 7 eggs and 5 larva, ranking 6th out of the 9 milkweed species.  Here is what it looked like on August 15th in my research plot.

I found my first egg on honeyvine in on July 19th, and by the end of the July had two 5th instars.  In the middle of September when none of the other milkweed had monarch larva, I counted a 5th instar on honeyvine.

I don't know how invasive it will be, so certainly wouldn't recommend planting honeyvine at this point.  It has exceeded my expectations for attracting monarch, however, so we'll see what happens next summer!

Next week:  Asclepias exaltata:  poke milkweed 

Whorled Milkweed (Asclepias verticillata)

Whorled milkweed is an attractive, skinny-leaved species that only grows 2 feet tall.  It is beautiful in a flower garden!  However, I'm a little concerned it may be too invasive for many gardeners.  By the end of the summer I did have a number of new shoots growing around my original plants, and online, some people consider it aggressive.   As you can see below, it doesn't look much like a common milkweed.  Here is what it looked like in my research plot on August 15th.:

I also planted whorled in a couple of other flower beds, and despite the insignificant leaf, they did support monarch larvae.  In fact, in my research plot this summer, whorled milkweed ranked 4th out of the 9 milkweed species planted, with 25 monarch, 15 eggs and 10 larvae.  As you can see in this photo taken July 31st, it even supported a 5th instar monarch larva.

Whorled milkweed blooms a little later than most milkweed, (July to September) and the white flowers attract many insects.  They are supposed to be deer and rabbit resistant, but my rabbits loved it, or at least loved to chomp the tops off.  I planted a wave of whorled milkweed beside monarda, so I am anxious to see how invasive it will be in the next few years.  In the photo below, the whorled milkweed is on the left (with the yardstick in the middle of them), and there is a wave of bee balm directly above them to their right.  Lantana, butterfly weed and black-eyed susan are above the monarda.

Prairie Milkweed (Asclepias sullivanti)

Prairie milkweed looks similar to common milkweed, but is less aggressive, and has smaller fragrant flowers.  It grows to about 3 feet tall, attracts hummingbirds, bees and butterflies, and has smooth, thick leaves.  In my research plot this summer, I had 24 total monarch (15 eggs and 9 larvae) on my prairie milkweed, just behind whorled, which had 25.

After only having milkweed in my garden for one year, the prairie species would be one of my recommendations for flower gardens.  However, It will be interesting to see how aggressive and hardy it is for me in the next few years.

Here is a monarch egg (about the size of a pinhead) on a prairie milkweed on July 19th, a month after planting.  A great majority of eggs are laid on the underside of leaves, like the one below.  Eggs hatch in 3-5 days.

On July 27th, a first instar larva is enjoying its meal of milkweed.  Monarchs go through 5 instars, molting between each, when its skin becomes too tight.  It will spend 2-3 days in each instar, for a total of 10-14 days as larva.

In my regular garden I had to make fences out of hard wire mesh to protect the milkweed that weren't inside my rabbit proof fence.  As you can see in the photo below, two larvae have moved off the plant to molt, a common occurrence.  Larvae will frequently take a day or two off from eating when they are molting.