One of my favorite aspects of my square meter photography project has been the chance to closely follow the lives of individual organisms over time. For example, I’ve closely followed the progress of the two butterfly milkweed (Asclepias tuberosa) plants within the boundaries of my square meter plot. The plants bloomed beautifully back in late June, which was great, though fewer pollinators visited the flowers than I had hoped. Perhaps correlated with that, only one seed pod was produced between those two plants. Since then, I have been watching that one pod very very closely…
This week, that pod finally opened up, giving me the long-awaited chance to photograph some milkweed seeds within my plot. As it turns out, it’s a good thing I was vigilant, because that pod opened up and emptied itself out out very quickly. Within only a few days, the pod went from tightly closed to completely devoid of seeds.
While many of the seeds were blown well out of my little plot, a handful got stuck on adjacent plants, giving me the chance to photograph them. Here are some photos of those seeds as they were coming out of the pod or after they got hung up within the borders of my plot.
To this prairie photographer, milkweed seeds are like candy – I just can’t get enough. As I’ve walked around this fall, I’ve had a very difficult time walking past any milkweed plant without stopping to photograph the silky seeds shimmering in the light. They’re just so FLUFFY!
(And yes, botanist friends, I know the fluffy part isn’t actually the seed, but is an ‘appendage’ called the coma – or less accurately, the pappus – that aids in wind transport of the seed. And the brown parts are actually the follicles that CONTAIN the seed. Yes, yes, and yes. Allow me this vulgarization for the sake of simplicity, ok?)
It’s getting a little harder to find milkweed seeds that haven’t yet blown away, but they’re out there. I keep seeing them as I walk through prairie and drive down the highway. I can hide the Halloween candy so I don’t snack on it all day, but who’s going to hide all those milkweed seeds?
I recently wrote an article for NEBRASKAland magazine about milkweed and the surprising number of milkweed species that can be found in Nebraska. (See the most recent online issue here). In total, there are seventeen species known to the state, and only a handful look anything like most people’s mental vision of milkweed – tall, with broad oval leaves and big pink flowers. Milkweed can be found in habitats ranging from wetlands to woodlands to dry sandy prairies, and can have flower colors of green, white, and orange (and, of course, various shades of pink and red).
Growing concern over monarch butterflies has raised awareness of milkweeds and their importance, but milkweeds are far more than just monarch caterpillar food. They have an incredible (in the sense that it doesn’t seem possible) pollination strategy, host an array of insect species that have evolved to handle the toxic latex produced by milkweed plants, and are among the most important nectar plants to many butterflies and other pollinators. We’re still learning about the relative value of each milkweed species as monarch caterpillar food, but there is no question about their overall beauty and diversity.
This is a great time of year to find many different milkweed species in bloom. See how many different milkweed species you can find in your favorite natural areas.
Here is a series of milkweed photos I’ve taken over just the last couple of weeks.
Last week, I attended a conference aimed at creating a statewide conservation plan for monarch butterflies. The meeting was really informative and thought-provoking. I learned a great deal about the ecology and conservation needs of monarchs from Chip Taylor of Monarch Watch and others, and was part of some good discussions about potential strategies to help the species recover. I thought I’d share some of what I learned from those discussions because they helped me better understand the issues surrounding monarch conservation. Any errors in the following are a result of my misunderstanding what smart and knowledgeable people told me, and I apologize in advance.
The monarch butterfly is a migratory species, but it takes multiple generations to make the migration from parts of North America to Mexico and back. Here in Nebraska, we’re part of the Eastern Population of monarchs, which extends from roughly the east edge of the Rocky Mountains to the east coast. The butterflies in this population leave their Mexico wintering grounds in late February each year and head north. They lay eggs in the southern United States and the monarchs produced by those eggs then head north into the northern half of the U.S. and the southern edge of Canada during May and early June.
During the summer, there are a couple generations of monarchs that mature and lay eggs without migrating. However, in mid-August and September, monarch adults get the urge to migrate and start heading south. Those that survive the trip usually reach the Sierra Madre Mountains of Mexico by early November.
Threats to Monarchs
There are two categories of threats to Monarchs: 1) Factors we can control, and 2) Factors we can’t. The big factor we can’t control is weather and the way it interacts with migration timing and butterfly survival. Weather can have a tremendous impact on butterflies, and many millions of butterflies are killed by hot weather, storms, or other events. However, since we can’t control the weather, we have to focus on what we can control.
There is a long list of human-induced factors that affect monarch populations. Those include the conversion of grasslands, roadsides, and field edges to row crops (largely facilitated by government policies) as well as farming practices that have nearly eliminated milkweed from farm fields. Pesticide use is another factor, including pesticides used for farming and pesticides used for other purposes, including mosquito control. Logging of forests in the wintering grounds of Mexico is another important issue.
I’d heard that the loss of milkweed from crop fields was a big deal for monarch butterflies, but hadn’t really understood why. At the conference, we heard that research has shown that about four times as many eggs/plant are laid on milkweed plants in crop fields as on milkweed plants in other habitats. (I’m not sure anyone understands why.) In addition, while the eastern population is spread across a huge area of North America, about 50% of the butterflies that reach Mexico are born in the cornbelt of the U.S. – the intensively farmed Midwestern states. Prior to the widespread use of glyphosate-resistant crops, milkweed was a pretty common inhabitant in crop fields throughout this prime breeding area for monarchs. Now that farmers are so much more efficient at weed control, we’ve lost the most productive egg-laying habitat in the country’s most important breeding area for monarchs.
Because monarchs can only be raised on milkweed, getting more milkweed plants in the landscape, especially within the cornbelt states, is a key part of increasing the monarch population. It’s likely that more than a billion additional milkweed plants will be required to stabilize the monarch population. Increasing milkweed populations to that extent will require a wide range of strategies. In addition, protecting and restoring the wildflower-rich grasslands and other natural areas that provide food for adult monarchs, as well as for thousands of bee and other pollinator species, is also vitally important.
One clear strategy is to plant more of monarchs’ favorite milkweed species in gardens, parks, roadsides, nature centers, and many other sites. In the north-central U.S., milkweed species such as common (Asclepias syriaca), showy (A. speciosa), and swamp milkweed (A. incarnata), are known to be favorites, while green antelope horn (A. asperula) is important in more southern states. You can find sources of seeds and plants at Monarch Watch or from the Xerces Society’s Project Milkweed website. Sites like monarchgard.com can help with garden and landscape design ideas.
More milkweed in gardens and landscaping can make a big difference, but an even bigger part of monarch recovery needs to come from a change in the way milkweeds – and the weedy, edge habitats they thrive in – are perceived by the public. Elimination of milkweed from roadsides, field edges, and odd corners and margins of our landscapes happens because we are uncomfortable with the “messiness” of those areas if they aren’t frequently mowed and/or sprayed with herbicides to make them look uniform in height and composition. Allowing milkweed and other wildflowers to thrive in those odds-and-ends habitat areas can have a huge impact on monarchs and other pollinators, along with pheasants, song birds, and many other wildlife species. Reducing mowing frequency and spot-spraying truly invasive plants – instead of broadcast spraying to kill anything that’s not grass – in these habitats saves both money and time as well.
The Role of Prairies?
Last week’s meeting also encouraged me to focus even harder on an additional aspect conservation I’ve already been working on – improving the contributions of native prairies and rangeland to pollinators. The experts at our meeting, along with other sources of information on monarchs, seem to be focused largely on milkweed and the kinds of farm fields, edge habitats and landscaping mentioned above. While all those are very important, I can’t help but think about the value of native prairies – especially in places like Nebraska where we still have millions of acres of grassland.
A healthy prairie with a diverse wildflower community is invaluable to bees and other pollinators, and also provides nectar resources needed by monarch butterfly adults. If that prairie contains vibrant populations of milkweed species that provide egg-laying habitat to monarchs, that’s even better. Many prairies don’t currently have strong milkweed populations. Some milkweed species are not strong competitors in a tight-knit plant community, and certain grazing and other management practices tend to further discourage milkweeds. Over the next several years, I am hoping to learn more about how to make prairies support stronger milkweed/monarch populations. Hopefully, we and others can help make North American prairies even better contributors to the survival of monarch butterflies.
Independence Day is this weekend. Fireworks have been going off in my my neighborhood for days now as people who apparently equate noise with patriotism are enjoying their right to put that feeling into action. Earlier this week, I was photographing a patch of common milkweed in front of our field headquarters at the Platte River Prairies and thought the flowers looked much like fireworks – but quieter. Maybe prettier too.
The attention paid to milkweed has increased dramatically over the last year or two as concern over the plight of monarch butterflies has grown. I’m excited to see that energy because it helps increase interest in broader issues of pollinator and biodiversity conservation. What’s good for monarchs (plant diversity, natural land cover – especially prairie, land management that favors milkweed, intelligent use of pesticides, etc.) is also good for bees and many other species, as well as broader ecosystem functioning.
I’ve been thinking about milkweed management in our Platte River Prairies for a number of years now, especially related to cattle grazing. Cattle like to eat the flowers off of common and showy milkweed (A. syriaca and A. speciosa) even in our moderately stocked patch-burn grazed prairies. The “deflowering” of milkweed and a few others species has pushed us to modify our management somewhat to make sure that every portion of our prairies is completely excluded from cattle at least once every 4-5 years so those species can bloom and reproduce. So far, that seems to have helped maintain healthy populations of those plant species, but we’re continuing to monitor and adapt our management as we learn more.
Milkweed plants are important to monarchs, but many other species as well. Their flowers are among the most popular nectar sources for many pollinators, and a number of herbivorous insects have evolved mechanisms to deal with the toxic sap and rely on the plants for food. Hopefully, the attention brought to milkweed by monarchs will help those other species as well.
Monday morning was cold here. If I remember correctly, it was about 4 degrees below zero when I decided to go for a walk with my camera. (Because, hey, what else would you do on a morning like that?)
There wasn’t much wind, so it honestly didn’t feel all that bad, especially since I was dressed for it. However, my camera was sure cold. It worked fine, but I had to keep an extra battery in my pocket (so it would stay warm) because batteries don’t last long at very low temperatures. The biggest issue, though, was that the viewfinder on the camera kept frosting over from my breath. Those of you who think photography is easy haven’t tried holding your breath every time you put the camera up close to your face…
As the sun came up, the prairie was populated with seedheads wearing little snow caps. Unfortunately, for whatever reason, I couldn’t seem to find a single one that photographed well. So, I ended up with this photo of milkweed seeds, in which you can’t even really tell it was snowy.
But trust me, it was cold.
Oh, and by the way – I took several versions of this photo and struggled to decide which I liked best. You might ask, “Chris, why don’t you just put a couple versions up and ask us which we like better?” Sure, that’d work great. I tried that yesterday with the bison photos. Twenty four hours later, well over 100 people voted, some contacting me outside of the blog, and the vote was almost exactly evenly split. A number of you tried to have it both ways, so your “vote” didn’t really help. The remainder of you did, at least, express an opinion, but in the end, there was no consensus.
I suppose I could take my cue from the United States government, and decide that since the readership is polarized I should just shut down the blog for a while. However, as an example to my country, I’ll take the high road and compromise. Both photos will be included in next week’s “best photos of 2013” feature. You have only yourselves to blame, though, when you look at through that photo montage and think to yourself, “Gee, this is nice, but it seems like there’s one too many images in it…”
(Seriously, though, thanks for voting. Both images were obviously popular. Some people felt very strongly one way or the other. Others liked them about equally. It was fun to read the reasons people chose one over the other. While there were some very thoughtful responses, my favorite was definitely the one from Mary, who chose photo B because the bison reminded her of her old uncle! As of the time I’m writing this, the vote count is 53 votes for A and 50 for B…)
A couple weeks ago, I posted a photo of a wasp (along with some other shots from a walk through one of our wetlands) and mentioned that I’d have a story about that wasp in an upcoming post. Here you go…
As I was looking for something interesting to photograph on my wetland walk, I noticed this paper wasp (Polistes fuscatus) nectaring on swamp milkweed (Asclepias incarnata). It was moving slowly enough – and was focused so strongly on nectar – that it was relatively easy to get some photos of it. In fact, I ended up watching and photographing it for about 10 minutes.
You may or may not know that most (all?) wasps in our prairies feed on nectar as adults, but feed invertebrates to their offspring. Many wasps are parasitoids – they capture and paralyze their prey, stuff it into a burrow or other similar structure, and then lay an egg on it. When the egg hatches, the wasp larva feeds on the paralyzed invertebrate. Most wasp species specialize in capturing a particular kind of invertebrate; some attack spiders, others go after cicadas, bees, flies, etc. Parasitoid wasps tend not to be aggressive toward humans, and are (at least most of them?) solitary – just a single female provisioning food for her nest. The mud dauber is an example of a parasitoid that is often seen in yards. Their mud tubes often show up on the sides of houses or inside garages.
The paper wasp is a little different. Paper wasps are social, and their familiar hanging nests are initiated each spring by a fertilized queen. Often, the queen will be joined by other females who help build the nest and feed the young. However, any eggs laid by those other females are eaten by the queen, ensuring her dominance. As the nest grows, multiple generations of wasps are produced, some of which become aggressive defenders of the nest – and that’s when the trouble starts for those of us who host paper wasps on our front porches.
Another difference between paper wasps and parasitoid wasps is that paper wasps catch and kill their prey (often caterpillars) rather than just paralyzing it. In fact, after they kill a caterpillar, they’ll feed chunks of it to their older larvae and then give prechewed pieces to younger larvae. You can read much more about paper wasps at this wonderful site from the University of Michigan. In addition, here is a link to a short YouTube video with fantastic footage of paper wasps.
Returning to the wasp I was photographing in our wetland…
As I watched the wasp, I noticed that his feet were starting to accumulate quite a few sticky pollinia from the milkweed flowers. Some of you who have been reading this blog for a while might remember a previous post that detailed the unlikely, but fascinating process of milkweed pollination. Essentially, the process relies on an insect accidentally sticking its foot into one flower, pulling out a pollinia (a sticky packet of pollen), and then stepping into another flower and losing the pollinia as it pulls its foot back out. Everything has to work just right for pollination to occur, and it seems as if it would hardly ever work, but the number of milkweed pods each fall are evidence to the contrary…
After the wasp accumulated a number of pollinia, it stopped feeding and started trying to remove the pollinia by running its legs through its mouth. I couldn’t tell if it was eating the pollinia or just removing them. Either way, it worked at it for quite a while, and it still didn’t get them all of (a good thing for the milkweed plant!)
Wasps are common visitors to flowers, but in many cases are less effective pollinators than fuzzy bees that get coated with pollen. However, as I’ve been paying particular attention to bees and other pollinators during the last several weeks, I have seen numerous wasp species on milkweed flowers. That probably works out pretty well for the milkweeds, since all they really need is a creature that steps into multiple flowers as it crawls around.
Paper wasps are not among most people’s favorite insects, and for good reason. Many of us have been stung by the aggressive defenders of a paper wasp nest. On the other hand, those stinging wasps are just defending their nest and queen – a noble and virtuous act, and something that’s hard to blame them too much for. Regardless, it’s also nice to see a paper wasp doing something that contributes to the greater good, like pollinating a milkweed plant. When I’m out taking photos of fluffy white milkweed seeds later this fall, I’ll be sure to mentally thank the paper wasp for a job well done.
The wind finally let up enough to do some close-up photography last weekend, so I went to a small prairie here in town and wandered a bit. Among numerous curiosities was the abundance of a tiny iridescent fly. I had to try quite a few times to get a decent photo of one. (They kept flying away!)
Not long after I got the above photo, I was ready to call it a day, and started walking back to the truck. I was hot and tired, but was drawn to a particular patch of milkweed. As I closed in, a small movement caught my eye. It was another of the shiny little flies. But in a bit of beautiful symmetry, it was being eaten by a shiny little spider!
Ok, I know milkweed seeds have been done to death by photographers. I, personally, have somewhere around a zillion milkweed seed photos. But milkweed seeds in the winter? With hoar frost? And a snowy background? That’s just magic. How can I not photograph that?
These photos are all from the same morning as those in last week’s photo of the week post. I’ve got even more from that morning saved up for future weeks… It was that kind of morning.
Not many insects can feed on milkweed. Milkweed plants produce a toxin that disables a protein in animals – a protein that facilitates important functions such as muscle contraction. Only a small number of insect species around the world have evolved ways to get around this challenge.
A new study published in the journal Science looked at 14 insect species that feed on milkweed and found that each had developed one of two ways to solve the milkweed toxin challenge. Ten of the insect species had gone through a genetic mutation that changed the protein in a way that the prevented the toxin from being able to act on it. The other four species had created a duplicate gene in the protein that allowed it to both carry out its normal function and alter itself to avoid being impacted by the toxin. You can see a summary of the study and a link to the full article here.
What’s most fascinating is that while these insects are only very distantly related to each other (they spanned three different orders of insects) they ended up with the same solutions to the milkweed toxin issue. It’s not like one insect species millions of years ago developed in a way that made it immune to milkweed toxin and then begat other species of insects that retained the same quality. These insects each developed the immunity INDEPENDENTLY. Fantastic.
Now, I have to be careful when talking about evolution because it’s easy to give the impression that these insects did something purposeful to change their bodies – they didn’t. They changed because natural selection favored individuals with certain genetic mutations that allowed them to eat milkweed without suffering changes to essential proteins. Unfortunately, evolution can be a hot-button topic these days, and one of the biggest reasons is that many people have a fundamental misunderstanding of how evolution actually works. If you’re interested, here is a link to website with a very brief but clear explanation of the process.
In the case of milkweed-eating insects, it’s easy to see that being able to eat a plant that competing herbivores can’t eat is a major advantage. Somewhere in history, a few lucky individuals ended up with a random genetic mutation that allowed them to eat milkweed without ill effects. Those individuals got a sudden leg up on their competition and, as a result, were more likely to survive and reproduce. What’s crazy and fun in this case is that multiple unrelated species ended up with similar genetic mutations of their proteins. They each accidentally “found” the same path to success. It’s a great world we live in.