Danaus plexippus feeding on bindweed

[Mike Canzoneri]

Hey Riley,

This one had me stumped! I thought for a minute you were pulling our leg
here. Then I did a search for articles with Monarch and bindweed and found
an interesting tidbit from Monarch Watch. I hope the mystery is solved, here
is the text from this URL:

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http://monarchwatch.org/dplex/1996/mweed2.htm

>From monarch at falcon.cc.ukans.edu Sun Aug 25 13:15:44 1996

Subject: Blue vine/sand vine- Cynanchum laeve

Laura Ellen Mitchell inquired about a viney milkweed which Brad Williamson
correctly pointed out is blue vine or sand vine with the scientific name of
Cynanchum laeve. Here are a few more notes about this plant and its
importance to monarchs.

This species is used extensively as a host plant by monarchs in late summer
in many parts of the midwest. Late in the breeding season (Aug-Sept) the
foliage of
these plants is usually in good condition, partly because of its
indeterminant growth (continually adding leaves). The common milkweed,
Asclepias syriaca, and
the swamp milkweed, A. incarnata, are often senescent at this time and they
do not appear to be as attractive to ovipositing females as they were
earlier in the
season.

Blue/sand vine can be quite common in developed areas. Look for it in
hedges, juniper trees and bushes and along fences. This species is often
confused with
bindweed to which it bares a superficial resemblance. Blue/sand vine is
often a pest weed in cornfields and I've had calls from farmers who want to
know how
all the monarch pupae ended up on their cornstalks because they couldn't see
any milkweed in their fields. They were aware of blue/sand vine but did not
know
it was a milkweed. Some of the most common predators of monarch larvae are
relatively uncommon in cornfields so its possible that in some areas large
numbers of monarchs are produced in cornfields on Cynanchum. In mid-July I
found 5 fifth instar(mature) larvae on one Cynanchum plant in my yard
suggesting some use of this species earlier in the season as well. Yesterday
and this morning I easily located several monarch larvae on Cynanchum. For
those
of you who raise monarchs, knowledge of this plant might be useful since it
can be used as a source of fresh foliage right up until frost and usually
long after the
more common milkweeds are no longer suitable.

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Cheers!
Mike


Riley Rice wrote:

> I've harbored this secret information for years (procrastination, that's
> all). I was browsing this forum for the first time and thought I might
> unload.
>
> In summer, 1991, near Dayton, Ohio (blackberry season - does that narrow
> it down?), I came across a D. plexippus caterpillar feeding on bindweed
> alongside a dirt road. The little guy was definitely out of its first
> instar (about 1 cm in length), so it was managing to survive OK (I saw
> no milkweed within easy view). I took it home and placed it on my
> milkweed. It did OK for a while then disappeared.
>
> Has anyone heard of such a food plant for this species?
>
> --
>
> Riley Rice
> http://home.att.net/~riley.rice/index.html

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