Monarch Butterflies in the US Virgin Islands

Defoliated plants show signs of severe caterpillar damage

Defoliated plants show signs of severe caterpillar damage

We became recently aware of some interesting, non-residents, visiting St. Croix. While working in the tree nursery, we first noticed some severe damage to some plants in the milkweed family. A quick investigation made us put away the pesticide and take our our cameras.

A female monarch butterfly lays a single egg

A female monarch butterfly lays a single egg

We spotted this female Monarch butterfly (Danaus plexippus) busy at work. Monarchs are a threatened, protected species. Many people say the Monarch is the king of the butterflies because of its beauty and that is how it gets its common name.  She and a few others were moving from plant to plant, laying a single egg each time. They were not easy for this novice to capture on camera. The adult butterfly may only live for 2 to 6 weeks and a female will lay roughly 100 to 300 eggs in her life.

 

Further investigation revealed both hungry caterpillars and freshly laid eggs on our plants. The Monarch butterfly has a very interesting life cycle and migration is one of the keys to their success. Their migration man be the most evolved pattern in any insect and their trip exposes them to several risks along the way.  Like many butterflies, they go through four life stages, egg, larvae (caterpillar), pupae (chrysalis), and adult butterfly. The whole process can be completed in as little as a month.  The species is on the move almost all the time.  Most descriptions of their migration focus on route that begins in Mexico and goes to Texas, south Canada and back again.  Clearly there is a percentage of the population that takes the long way around and goes through the Caribbean.

A pair of Monarch caterpillars feed on milkweed.

A pair of Monarch caterpillars feed on milkweed.

 

This link from a group in Texas tells you where are they now?

 

Many of the caterpillars on our plants have formed cocoons already. We expect new butterflies to emerge soon and begin their northward migration. We will keep you posted right here.

A cocoon or chrysalis is formed and the new butterfly will soon emerge.

A cocoon or chrysalis is formed and the new butterfly will soon emerge.

Comments

Melissa E. Keyes2015-05-20 16:56:35

Do they go anywhere else besides Mexico? Someplace in Venezuela, for instance? Is this known?

bdaley2015-05-28 12:57:35

I included a bunch of hotlinks in the blog post that will take you to other monarch projects. Most of them are small scale project with a regional focus. Im certainly no expert, but after reading a bunch of them, my understanding is that the vast majority of monarchs overwinter in the low mountains of mexico. I have not read anything about smaller populations overwintering in venezuala or any other place. I also did not find much of anything written on the migratory path that takes them through the Virgin Islands

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