Sunday, June 22, 2014

Tales of the Monarch and Black Swallowtail

They're here! Black Swallowtail caterpillars have arrived (already) in my gardens.

Below, some pretty butterfly/caterpillar photos from a past summer:

In 2011, I wrote about the life cycles of the Black Swallowtail and Monarch and I thought you might like to read about them again.

This is one of the earlier instars of the Black Swallowtail caterpillar; it will turn to the green/yellow/black (first photo on this post) as it gets older and sheds this skin.

An interesting fact about the life cycle of the black swallowtail: caterpillars that pupate earlier in the summer leave the chrysalis as adult butterflies in about ten days. 

Caterpillars that pupate later in the season may experience diapause, a delay in development which is a physiological state of dormancy used as a means to survive unfavorable environmental conditions, such as temperature extremes, i.e. winter, drought, or reduced food availability. What this means is that these caterpillars rest over the winter in their chrysalis and hatch as adults in the spring time. This is one reason that some environmentalists say you should delay cutting back/cleaning up your garden waste from fall to spring. (I'll still be cutting mine back, but I'll be very mindful and observant of possible chrysalis in amongst my plants.)

Now, a little information about Monarchs.

Monarch caterpillars on the butterfly weed. The life cycle of the Monarch is incredible. The cycle begins with a tiny egg, which is generally laid on some type of milkweed.  When it hatches in about 4 days, it is as a tiny caterpillar that eats and grows for about two weeks.  When I have been observed these wonderful caterpillars (and black swallowtail caterpillars as well) over two weeks, their growth rate was simply incredible.

I've lost track of the butterfly-to-be when it forms a chrysalis. I've heard that the caterpillar moves from the milkweed to a suitable (hidden?) location. It is in the chrysalis for about 10 days before emerging as a beautiful butterly. Its life as a butterfly lasts from 2-6 weeks.

Note the larger caterpillar and smaller one are sharing the same leaf! I thought this made an interesting photo.

Speaking of interesting, did you know that there are 4 generations of Monarchs born each season? It all begins in March/April when the first generation is born and goes through the 4 stages of the life cycle: egg, caterpillar (larva), chyrsalis (pupa), adult butterfly. In May/June the cycle repeats for the 2nd generation. July/August is when the 3rd generation is born.

In September/October the 4th generation is born - egg, caterpillar, chyrsalis, adult butterfly...but THIS generation does not die. It migrates and lives for 6-8 months in Mexico or Southern California. The Monarchs begin awakening and mating in February/March of the next spring and then lay their eggs. After living for much longer than the other 3 generations, with their purpose met, they finally die. (Information from


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