Now only 3 (Monarch larvae)

Paul Cherubini monarch at saber.net
Wed Oct 31 21:41:34 EST 2001


Ron Gatrelle wrote:

> Last post I noted how we got an A. tuberosa to still be fully leafed this
> time of year.  This leads me to this question.  Do southward moving
> Monarch's not oviposit simply because the suitable hosts are dried up.  If
> green plants are found will they oviposit even though in the migration
> mode???

Ron, the reproductive state of fall migrant monarchs is not black
and white.  While a majority of Sept/Oct. fall migrants are in reproductive 
diapause and will ignore suitable milkweed plants they encounter en route to 
Mexico, a small percentage of the migrants breaks diapause 
and will lays eggs on any available milkweed. Thus it is
common to find monarch eggs and caterpillars in the southern states
in September, October and November.   

How small a percentage of the migratory population breaks diapause? 
Well even if it is only 2% out of a population of 100,000,000 butterflies, 
2,000,000 reproductive butterflies is ALOT of reproductive butterflies.

Some fall migrants also break diapause deep down in Mexico
and lay eggs on the milkweeds growing in the vicinity of the Mexican
overwintering sites. 

Still another angle on all this is that Mexico is not the sole destination
of fall migrants. Some move down through Florida and even end
up in the Bahamas and Caribbean.

http://www.saber.net/~monarch/urquhart1971-81.JPG
http://www.saber.net/~monarch/MW1996.jpg
http://www.saber.net/~monarch/urquhart1964-71.JPG
http://www.saber.net/~monarch/urquhart1982-88.jpg

Paul Cherubini
Placerville, Calif.

 
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