Desertification Iowa Style and the Decline of the Monarch

Yale’s e360 has an excellent interview with Dr Orley Taylor of U of KS on the subject of monarch butterfly decline.

What we’re seeing here in the United States is a very precipitous decline of monarchs that’s coincident with the adoption of Roundup-ready corn and soybeans. The first ones were introduced in 1997, soybeans first, then corn. By 2003, 2004, the adoption rate was approaching 50 percent, The use of Roundup ‘has effectively eliminated milkweed from almost all of the habitat monarchs used to use.’ and then we really began to see a decline in monarchs. And the reason is that the most productive habitat for monarch butterflies in the Midwest, in the Corn Belt, was the corn and soybean fields [where milkweed, which monarchs feed on, grew]. Before Roundup-ready crops, weed control was accomplished by running a tiller through those fields and chopping up the weeds and turning over the soil, but not affecting the crops. The milkweed survives that sort of tillage to some extent. So there were maybe 20, 30, 40 plants per acre out there, enough so that you could see them, you could photograph them.

The glyphosate used in agriculture has tripled since 1997, when they first introduced these Roundup-ready crops. The developers of these crops not only provided the seeds that were glyphosate-resistant, but they also provided the glyphosate — the Roundup. And, boy, that was a pretty good system. You could make money on both, right?

For the farmers it looked good too. If I was a farmer and I was holding two jobs to keep my farm and I didn’t want to have my rear end sitting on the tractor too long, I would use that product as well, because the ordinary mechanical tillage took a lot more time and cost a lot more money.

e360: This is not the sort of thing people originally worried about with genetic engineering — it’s not a mutant gene getting loose, it’s not food safety. It’s just a change in conventional farming practice.

Taylor: It’s a collateral damage issue. And one of the things that we’re worried about now is that it looks like there’s going to be a lot of collateral damage from the use of various herbicides and pesticides coming down.

You’re basically creating a desert out there, except for the corn and the soybeans.


  1. Does anyone know of any estimate of North American monarch butterfly populations before the prairies were farmed? I suspect that this is one of those man-gave-and-now-he-taketh-away things - that is, monarchs boomed when man increased or improved the habitat suitable for milkweed and they're doing badly now that all that (unintentional, inefficient) largesse is shrinking. Sad, but not exactly a crime against nature.

    A similar thing is happening with the turtle dove in Britain. It thrives on the seeds of weeds that like corn fields (and on seedcorn when they can find it) so its numbers and range kept increasing until about fifty years ago, when weed control started becoming more effective. There are other factors - increased hunting in Spain and in other countries it migrates through and competition from a similar but non-migratory dove that arrived fairly recently (plus of course the usual shoehorning of climate change into the narrative) - but the main cause of the dove's local decline is probably a local decline in the seeds of its favourite field-loving weed, fumitory.

    So, any evidence of a similar boom-bust story with the monarch butterfly and milkweed? The bust is well covered but what about the boom? Did it exist? I spent a while googling but no luck. (Not helped by a shitty Internet connection. At least twenty drops in the last hour! If things don't improve, I think I'll go back to reading books of an evening.)

  2. There is more on the matter here:

    University entomology departments have traditionally been within a College of Agriculture (or Food and Agricultural Sciences or the like) rather than within biology > College of Arts and Sciences. Thus their focus and financing has been for killing organisms except for crops. Recently, due in part to decline of various pollinator species, more attention is given to ecology.

  3. Pingback: Another Week in the Planetary Crisis, April 7, 2013 – A Few Things Ill Considered

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