Ten days ago, I wrote about monarch butterflies returning from Mexico and flying much further north than is typical, and some of the risks they face because of that. Many of you responded with your own similar observations and stories of monarchs across the country. Since writing that post, I’ve spotted numerous monarchs both at our family prairie and in our Platte River Prairies, and reports to Journey North show monarchs have traveled even further north than we are here.
Earlier this week, my wife got to watch a monarch laying eggs on some small whorled milkweed (Asclepias verticillata) plants in our backyard prairie garden. A monarch (same one?) came by when I was around too, so I snuck out and tried to get photos of it but it was too cagey. At the end of last year, Kim and I were talking about how surprisingly fast the couple of small whorled milkweed plants we’d gotten for the garden had spread. Now we’re worried that we don’t have enough whorled milkweed to support all the eggs that have been laid on them!
A monarch egg on whorled milkweed in our backyard.
Usually, the monarch laid only a single egg per plant, but some plants had as many as three on the same small plant. Hopefully, those caterpillars will be able to make their way to surrounding plants if they overwhelm the ones they start on.
Yesterday, I went walking in our Platte River Prairies, hoping to find some eggs there as well. I was looking for common milkweed (Asclepias syriaca) but all I found was more whorled milkweed. Sure enough, I found eggs on some of those plants too, and even spotted a couple tiny caterpillars. All the plants I found were in prairie patches we’d burned and grazed last year. I’m guessing the monarchs had the same impression I did of that grazed habitat – it’s sure easier to find tiny milkweed plants when there aren’t a lot of taller plants and thatch hiding them!
This tiny little caterpillar was busily munching away on whorled milkweed in our Platte River Prairies. It was just a couple millimeters long.
Whorled milkweed doesn’t usually get the accolades or attention it deserves. In our prairies, it is often most abundant in areas where native prairies have been degraded by a long history of overgrazing and broadcast herbicide use (before we acquired the properties). The plants are relatively small (often less than a foot tall) and have small white flower clusters and skinny seed pods. When we’re harvesting seeds for our prairie restoration work, we try to get enough seed to ensure the species will establish in our plantings, but probably haven’t always worked as hard as we should at it.
Whorled milkweed is often overlooked and underappreciated, but is certainly proving its worth this spring.
The monarch eggs and caterpillars I found yesterday were in a restored prairie we’d seeded back in 2000. The patches of whorled milkweed I found were over 15 feet in diameter, and some contained well over 100 plants. I’m awfully glad now that we took the time to find and harvest whorled milkweed seeds during the summer of 1999, and wish we’d harvested even more. Nevertheless, the plants that established back in 2000 have spread successfully and are now helping to rear the next generation of monarch butterflies. When those caterpillars emerge as butterflies, they’ll find themselves in the middle of a large and diverse prairie community, full of flowers for them to feed on. Eighteen years ago, that same location was a cornfield. Today, it is giving some way-too-early monarchs a chance at survival.
This plant had both an egg and an already-hatched caterpillar. Hopefully, as it grows, it will find not only sufficient milkweed, but also abundant nectar resources for its adult life. (You can see a larger and more clear version of this image by clicking on it. Maybe you can figure out what the little white bump is on the caterpillar’s back… Part of the egg? Something else?)
The Prairie Ecologist 
Hi Chris! An excellent, and enlightening, story that we will share on our FB page and at our Texas Pollinator PowWow next week. Thank you. As to your question, with my 14 year old laptop (that’s NOT a typo!) it’s hard for me to see more clearly, but I’m wondering if the little bump may not be a wasp larva emerging. Carrie
Carrie, I had that thought too. I wish I’d seen it when I was there so I’d have documented it better. I was too worried about getting the head and egg both sharp in the photo and didn’t notice the protrusion (?) until later.
It looks like it is behind the caterpillar, not on the caterpillar, but I it certainly could be. I was thinking it was the remains of the egg case it emerged from.
BTW, do you or anyone know whether an emerging monarch caterpillar might eat other eggs laid on the same plant to reduce the competition?
Yes, they do, Patrick. We’re very blessed to have Dr. Lincoln Brower as our monarch mentor for the Texas Pollinator PowWow, and I fortunately was able to find this link to a similar question asked of him, and his VERY enlightening answer: http://www.learner.org/jnorth/tm/monarch/Egg_LPB2.html
Thanks! Yes, very enlightening answer. I have seen monarchs avoid plants with other eggs on them, and cannabalism is probably why.
Great story. We’re a milkweed/native seed producer in Winters, Ca. We grow over an acre of each of Asclepias fascicularis and Asclepias speciosa.
Keep up the good work.
Jeff
Jeff Quiter Nursery/Habitat Manager Hedgerow Farms 530 662 6847 office 530 908 6184 cell 530 662 2753 fax
On Fri, Apr 28, 2017 at 9:38 AM, The Prairie Ecologist wrote:
> Chris Helzer posted: “Ten days ago, I wrote about monarch butterflies > returning from Mexico and flying much further north than is typical, and > some of the risks they face because of that. Many of you responded with > your own similar observations and stories of monarchs across ” >
I love whirled milkweed! There is a spot on 169 hwy near the I-435 exit in Missouri where a great stand is growing. I watch it every year in hopes that it doesn’t get sprayed with chemicals! <3
One lady said several years ago that her garden butterfly plants
weeds were completely stripped of leaves, so she moved the caterpillars to wild milk weeds and they continued to eat.
I have never seen an egg or caterpillars on the milk weed I have. I believe eggs are not laid on them as there is no native grass or suitable weeds around to go to for their pupae stage. Any comments on this?
I did not have any plants that would be suitable for egg laying when the early Monarchs were here.
Could it be that there are no native NECTAR plants around? Try finding out what nectar plants that would grow in a prairie environment and plant them in your yard and if you attract adult monarchs, you will most definitely get fertile monarch females to lay eggs on the milkweed. Try that and I bet you’ll get egg-laying! ;-)
The caterpillars may not be too choosy
when deciding on a place to pupate. The
authors of a book I’m reading documented seeing
15 caterpillars. Later they found 6 chrysalises
attached to plastic strands of a deer fence but
but the rest were hidden in the garden. I’m assuming
the milkweed was planted along this fence.
I had Monarch butterfly caterpillars on butterfly milkweeds in my suburban yard only one year out of the last six. These butterflies probably tend to avoid suburbia for egg laying even though they use my garden extensively to fuel up on nectar for migration.
Excellent! We have monarch larval use of broad-leaf and western whorled milkweed here in the Texas Panhandle; research underway.
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