Sunday, September 30, 2012


Monarch laying eggs on Sept. 30th

She laid 4 eggs on this milkweed

Custom's House Museum

Yesterday, I left my home in NW Ohio and traveled to Key West, Florida. The last Monarch from Waystation No. 613 in NW Ohio was released and no caterpillars were seen for several weeks. I raised and released 39 Monarchs from eggs collected off my milkweed plants. I saw -0- eggs being laid or caterpillars for weeks in NW Ohio, until I visited the Custom House Museum off of Malory Square in Key West, Fl.

The flower garden in front had a half dozen milkweed plants and, to my surprise, a female Monarch was visiting them.  I counted 3 eggs on one plant and had no idea Monarchs were still laying eggs on the last day of September, even the southernmost ones. The location of this Monarch and her eggs is about a one minute walk from the southernmost tip of the U.S. in Key West, Fl.  

The weather was sunny and in the low 80's. The Monarch looked a bit "worn", so at first I thought she may have been a migrant from up North, until I witnessed her laying eggs underneath the milkweed leaves. I couldn't fathom a northern migrant doing this! The half dozen milkweed plants planted in the flower garden in the front of the Key West Custom's House Museum had a variety of flowers, so someone must have planted the milkweed on purpose, knowing their value to Monarch butterflies. The milkweeds 
were well taken care of. Hats off to whoever you made my vacation, just witnessing a Monarch egg-laying the last day of September, an event never seen in NW Ohio!
Learn more- Florida Butterflies
I decided to find out more about Florida Monarchs. Do they stay year round? Do they migrate to Mexico? The University of Florida (IFAS Extension) provided me with the answers. Because of  the warm climate and continuous availability of host plants, much of Florida's monarch population stays in the state year-round and breeds continuously throughout the year. Since I took the egg-laying photos (above) a stone's throw from the southernmost point in the U.S., that's why this female was laying eggs in front of the Custom's Museum in late September. Year-round residents are more common in southern Florida, as cold winter temperatures in northern Florida can kill monarchs at any life stage. My stay in Key West from September 24 to October 8 never had below 85 degree temperatures during the day and 73 degree temps at night. the University of Florida data also reports that, in addition to resident populations, the state also hosts migratory monarchs from northeastern North America, but there are competing hypotheses regarding how these migrants travel to, from, or through Florida. These northern migrants, I would assume, have under-developed reproductive organs, so do not breed or lay eggs while passing through Florida. So, I'm assuming the female laying eggs was a resident Monarch.

Dr. Oberhauser's research
That is what I assumed, however, until I came across a report by Dr. Karen Oberhauser. She said that Florida is a terminal destination for migrating monarchs from the northeastern United States and southeastern Canada. She posits that these monarchs fly into Florida but don't disperse out, making the Florida population a "sink population." In southern Florida in particular, the warm climate likely stimulates monarchs' reproductive behavior, which upsets hormonal balance and causes them to lose their ability to migrate north. Thus monarchs that migrate to southern Florida may stay and become part of the local breeding populations. Recent research by Cristina Dockx and colleagues, however, suggests that some migrants start to return north each spring, and after several successive generations they eventually reach their natal grounds in northeastern North America.

Learn more
It is also possible that Florida is a stopover for migrating monarchs on their way to the Mexican wintering grounds. Migration from Florida to Mexico remains largely hypothetical, but researcher Gary Noel Ross has observed thousands of monarchs on oil platforms in the central Gulf of Mexico, indicating that they cross from Louisiana to northeastern Mexico each fall. However, a recent study by Elizabeth Howard and Andrew Davis found that monarch roosts along the East Coast flyway lagged behind roosts in the central U.S. flyway, suggesting that monarchs migrating down the East Coast are less likely to make it to the Mexico wintering site. Christina Dockx and colleagues contend that monarchs found in St. Marks National Wildlife Refuge (Florida panhandle) are heading to Mexico, whereas those found in southern Florida spend their winters either in southern Florida, Cuba, or other areas of the Caribbean.

I was fascinated with this research, mostly hypothetical, I might add...and that's what makes it so intriguing. I've also seen Monarch butterflies in the southern Bahamian out islands, like Exuma, during the fall months. Could they have been east coast migrants? Or, are they residents of these Bahamian outer islands all year long? I have photos and a post about Monarch butterflies on Exuma Island, Bahamas.

Robert Morton, M.Ed., Ed.S believes urban sprawl can be offset by creating wildlife-friendly spaces in America's 25,000,000 lawns, one yard at a time! Click HERE to learn why. A portion of Ad sale revenues will be donated to Monarch Watch. Do you have a wildlife-friendly space? Please share it by contacting us