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  • Andy Davis

Thoughts on Anurag Agrawal’s new book, Monarchs and Milkweed

Greetings everyone,

I just got a copy of the new book, Monarchs and Milkweed, by Anurag Agrawal, a long-time milkweed and monarch scientist from Cornell University. Anurag’s book just came out this year and there have been a number of press releases and articles written about it. I’m going to put in my two cents about it here too. I’m not really giving a full-on review here (mostly because my time is limited), so let’s just consider these my thoughts on the book, as someone who knows this subject.

So the first thing that struck me about this book, before I even opened it, was it’s thickness. It’s a hefty book, which is rather impressive considering it was all written by one person. Anurag, apparently, has a lot to say! I wonder how he found time to write this while keeping up with his academic duties, family, etc!

The theme of the book, as the title suggests, is on the complex relationship between milkweeds and monarchs, and the science behind this. I know that this is something that Anurag and his lab have studied for many years, so this material is straight from the horse’s mouth, so to speak. The book also gives a nice overview of the basic biology of the monarch, with an emphasis on the larval stage, since that is where Anurag’s lab has done the most work.

The book is broken into 9 chapters, which cover topics such as the monarch migration, the life cycle, the life of a caterpillar, and also, the population status of the monarch. Throughout each chapter, Anurag tells the reader what is known about each topic from the scientific literature, plus he interjects thoughts of his own and evidence gathered from his own lab on these topics. This last part is something I can appreciate as a scientist. By interweaving personal anecdotes and stories from his own lab’s research endeavors, he provides the reader with a glimpse of what goes on in the research lab of a scientist, thereby pulling back the curtain of science, so to speak. I like this a lot, and I wish other scientists did more of this. I’ve blogged about this issue in the past – about the current problem we have in this country with a growing disconnect between scientists and the public. This disconnect is getting ever bigger now especially with our current president fanning these anti-science flames. So because of this, I really appreciate it when any scientist takes time to step out of the jargon-laced world of their ivory tower and tries to connect with real people.

That being said, the one recurring thought I had while reading this book, was that despite his efforts to boil down the science surrounding the monarch, I’m not sure if he went far enough to appeal to the everyday, butterfly-loving, garden-planting, joe-public. As I mentioned earlier, the book is thick, and it has a lot of science (even some graphs – gasp!), and that right there might be a turn-off for some. To be fair, perhaps Anurag did not intend for this to be a simple coffee-table book of fluffy butterfly pictures. We already have plenty of those books, and some of these look like they were written by people who went to the University of Google. But this is the heart of the problem we’re facing today in science. We (scientists) need to be able to reach these non-science people, especially since some of these are the people who are working on the front lines of monarch conservation. These are the people who are planting milkweeds, making butterfly gardens, etc., and it is imperative that they be aware of and understand the current science around this critter. If they don’t, then they go off and plant tropical milkweed, or try to rear 6000 monarchs in their basement (I blogged about this too), or do something else that actually hurts the monarch rather than helps. Conservation actions should always be based on science, in my book, but this can't happen if the science is not communicated effectively to the conservationists! It's a chicken and egg thing. I might blog more on this issue in a future post, because it's a big issue in today's world and with the monarch especially.

Speaking of thorny conservation issues, I noticed that on the issue of tropical milkweed, Anurag wrote a just few lines about it (I can’t remember in which chapter), and I saw that his attitude about it is a little cavalier. He said the monarchs like it and it’s pretty, so he doesn’t see a problem. This attitude might stem from the fact that he lives in central New York, where this milkweed, if planted, dies back in the fall like all the rest, and is therefore not problematic. This is unfortunately, the same attitude that most other northerners have on this plant – it’s not a problem here, so what’s the big deal? Here is the deal – and this is something that Anurag should know – the monarch’s life cycle is all connected, from winter, spring, summer, and fall. Tropical milkweed grows year-round in the southern states, and this causes the monarch parasite, OE, to build up on it, thereby causing extremely high levels of infection in the monarchs at these locations. We have good evidence for this - see a blog from a while back on the evidence. But (and this is a big but), monarchs traveling north in the spring from Mexico pass through these local disease hotspots and deposit their eggs on these very milkweeds. These progeny then become infected, and they may even try to continue the northward migration, spreading more OE as they go. So in effect, these southern tropical milkweeds can give the OE parasite a head-start each year, which would not have happened without the tropical milkweeds. This then causes a greater prevalence of OE in the entire population, increasing mortality and thereby reducing overall numbers of monarchs everywhere. This is why it matters to northerners if southern gardeners have tropical milkweed.

OK, enough about tropical – why did I start talking about that anyway?

So one thing that I did like a lot about the book was the way Anurag described all of the various critters besides the monarch that make milkweeds their home. He describes a dozen or so other bugs, like milkweed bugs, beetles, aphids, etc, and he paints a picture of an entire community, or ecosystem, that lives and thrives on milkweed plants. The way he describes standing in fields of milkweed and watching nature play out on these plants makes you want to do the same. Some of these critters only eat milkweed, just like monarchs. This is a narrative I like, because it emphasizes how milkweeds are not just for monarchs, which is something that many home gardeners don’t appreciate. Too often I see comments on monarch facebook group sites, or email queries, about how Joe-the-gardener planted milkweed for monarchs, and wants advice on how to kill the other bugs that have "infested" his plants. This drives me nuts. It’s as if Joe should have put a sign out on the plants saying “for monarchs only.” These people need to know that there is a community of critters that all use milkweeds.

The last chapter of the book is devoted to another juicy topic, that is, the more recent work Anurag has done on the long-term decline (or really the lack of one) in the eastern monarch population. Most of this material comes from a paper that came out last year written by Anurag and colleagues (Inamine et al 2016), and which I blogged about at the time. It was a pretty influential paper because it argued there is plenty of milkweed for monarchs. In a nutshell, that study showed that the population decline is only seen at the overwintering stage, and during the spring the monarchs appear to bounce back every year, leading to a lack of a long-term decline in the summer and fall population. This work is consistent with a number of other studies, some conducted by me, some by others, so it’s solid. However, not all monarch scientists are in agreement over this, and this debate is ongoing. See the recent paper that I blogged about for more on this debate. But one thing that also was interesting in this chapter was that Anurag tells of a trip he took throughout the eastern seaboard a couple years ago, where he conducted an informal survey of milkweeds in various states in the monarch breeding range. He reports finding milkweed everywhere, and his intuition tells him that there is plenty of milkweed to go around right now. I definitely appreciated this observational evidence, as I suspect not many people (and who know how to identify all 100+ milkweed species of North America) have done this.

So in the end, I enjoyed reading this book and I recommend it for people to add to their collection of monarch books. I hope others appreciate it too, though I worry that my enjoyment of this book was because I understand (and enjoy reading about) the science. Nevertheless, it is safe to say that this book should be read by everyone involved in monarch conservation.



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The science of monarch butterflies

A blog about monarchs, written by a monarch scientist, for people who love monarchs

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