[LEPS-L:8039] Re: diapause in midea

Chris J. Durden drdn at mail.utexas.edu
Wed Nov 29 13:29:23 EST 2000

My "earliest" record for *A. midea* in Austin, Texas is for New Years Eve!
Probably triggered by warm weather after cool. The following 3 days were
snowy - the last snow we have had here for a number of years.
............Chris Durden

At 12:10  29/11/00 -0500, you wrote:
>Neil Jones wrote (regarding Ron's discussion of Anthocharis):
>> I'd be interested to see a scientific referrence for this.
>> My understanding of this in Orange Tips is that emergence is triggered
>> by warmer temperatures after a colder spell. I have had Anthocharis
>> cardamines lie over like this when kept indoors. I have also had
>> Pieris napi emerge in February on a windowsill in a cool room
>> after the frost had got at them for a while a few weeks before due to
>> poor heating. We don't suffer from low humidity here. It rains a lot.
>> It hasn't rained today yet but its only one o'clock.
>There could be an interesting behavioral difference between the continental
>species (or within species according to local humidity).  Down in the
>southwestern part of the U.S., I am convinced that the Anthocharis species
>emergence is linked to rainfall.  I'm sure there is also a temperature
>component - these are often among the first spring leps to emerge (just as
>soon as daytime temperatures begin to rise).  Because we go through more
>drought years than we do wet ones, the well documented mass emergences
>following heavy (and early) spring rainfall would suggest that such a
>trigger does exist.  This is especially true with the desert species A.
>I have enjoyed chasing A. midea on the east coast and in Texas where
>hundreds of individuals were flying during early spring.  I don't know how
>much fluctuation there is with this species based on rainfall - but then the
>east coast is generally wetter than we are out west anyway.  They have had
>drought years recently - but long term (multi-year) droughts would likely
>have a significant impact on population dynamics beyond delayed emergence.
>Anyway, discuss on - this topic interests me as well.
>Mark Walker.


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