Monarchs, roundup & other pesticides

Gaia Nature info at
Sat Aug 27 11:49:13 EDT 2005

One thing we have learned (the hard way) through our many years of breeding
thousands of Monarchs is that you should never collect the milkweed growing
near a corn field.
This year again we lost all of our first week of production because of fresh
nice milkweed that was picked up on the edge of a corn field. The
caterpillar eats the milkweed for a while then they turn black or just stop
eating in the last instars & die. As soon as I saw this happening (again) I
figured out that the problem were their food, we switched to another wild
growing & untreated field and we immediately started to have a good monarch
culture again.
I know that the farm where we picked up the "killer Asclepias syriaca" use a
fairly large quantity of roundup to try & kill the plant before corn starts
to grow (since it's not GM roundup ready corn) but it doesn't seem to kill
the milkweed, leaves become yellow & weird & twisted growth appears but it
doesn't die. 
So the roundup residue might be the killing agent, but there is another
possibility: The seed treatment. There is a pink fungicide and larvicide on
these seeds and If roundup is not the killer, then this larvicide might
spread with the early rains to the lower milkweed roots in soil and get
inside the milkweed foliage, then affect anything that tries to eat the
It would be interesting to learn how long this larvicide can stay active and
if most crops use this, being a standard procedure. 

I would be interested to read thoughts on these observations

Dave Clermont
Butterfly breeder

Neil responded to my query with:

> The data cannot be relied upon to provide the results you are looking
> for because there aren't enough of them.

First, I have no ax to grind here--and am not looking for any results.
I was merely asking how Neil's comment about tag recovery being
determined by local weather at the overwintering sites had any
relevance to the problem at hand, which concerned the ratio of eastern
to mid- western tags. That question he did not answer.

I agree that the numbers Paul found and reported are small, and make
firm conclusions about trends hard to support. There are, however,
clearly more midwestern than eastern recoveries (subject to change
when all the data are in).

As to whether GM crops are harmful or harmless to butterflies (or to
other organisms--they are certainly as hard on weeds as they are
designed to be!)--that depends on the specific organism, and also
requires one to take a long view of the situation. Is the number of
milkweed plants in the midwest before the advent of GM crops larger
or smaller than the number before Europeans came to the New World? Is
the _current_ number larger or smaller? Are the masses of Monarchs in
the midwest an old event. or something of recent origin due to agri-
culture? I have no idea, but the Monarch researchers may know some-
thing about this.

> You know Ken up there in Alaska you don't seem to understand what
> modern agriculture is doing to butterfly populations.

Well, although that kind of thing is not a major problem in Alaska, I
_do_ read, and have visited the lower 48 states a number of times
since I moved to Fairbanks. I recall reading about the effect that loss
of the hedgerows had on English butterflies, for example... But what
I would like to see are data on the abundance of milkweed in the mid-
west through history. Is the pattern of weedkiller spraying in GM crops
allowing significant amounts of milkweed to survive? Is that amount,
whatever it may be, larger or smaller than the amount present before
the introduction of large-scale farming?

	Similar questions would arise for any butterfly foodplant in the

		Ken Philip


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