Monarch Butterflies

Finally!  The monarchs are late this year, or they were hiding.  I have finally seen 2.  It makes me wonder...there used to be a lot of monarchs here, but 2 Augusts ago, a lady came by and harvested cocoons for her school.  Maybe there are lots where she took them?  It takes 4 generations of butterfly to migrate to Costa Rica and back.  There is lots of milkweed here, even more than before.  Why are the butterflies not here in even larger #s?  As far as a declining population is concerned, I resist that this is part of an overall trend, as the population here was very healthy UNTIL the cocoons were exported.