Predicting When the First
Spring Generation Will Emerge
It's early May, and the monarchs from Mexico have traveled
as far north as shown on the map below. When and where will their offspring
emerge and continue the northward migration? Our goal is to show when
we can expect monarchs to emerge at the places where the monarchs from
Mexico have now arrived.
Print out a copy of Journey North's monarch migration map. Look carefully
at the legend. Notice that the different colors show the range of dates
when FIRST monarchs were sighted.
As of May 2, 2001
There were probably many, many monarchs in each place where one monarch
was sighted. And what do you think the FEMALE monarchs were doing at
all of those places? (Answer: Laying eggs--LOTS and LOTS of eggs!)
we assume eggs were laid where these monarchs were sighted, when would
the next generation of monarchs emerge in these places?
First you need to consider how long it will take for a generation to develop.
Depending on temperature, the time for development varies. But an estimated
number of days the monarch spends at each stage of development is:
Development Time for a Monarch Generation
number of days between generations
Let's assume that it takes 32 days for a monarch to develop from an egg
into an adult. Now make a new legend for the map. Our goal is to show
when we can expect monarchs to emerge at all the places where the monarchs
from Mexico have now arrived.
|First Monarch Sighted
||Next Generation Should Emerge
|Before March 15
|Mar 15 - Mar 28
|Mar 29 - Apr 11
|Apr 12 - Apr 26
When and where will the offspring
emerge and continue the northward migration? (Click here
to see new map and legend.)
(IMPORTANT NOTE: In reality of course, monarchs are now at different stages
of development all across their range. This is due to the differences
in arrival dates, the different temperatures at each place, and other
factors that affect development time. This question is only intended to
help estimate the timing of monarch generations.)
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