Monarchs say hello to the warm weather

Monarchs migrate through Cape May County to spend their winter in Mexico.

You’re sitting on the beach, watching the waves when you see a glint of orange fly by. A  few minutes later, you see a few more spots of orange. 

Butterflies. You think. That’s weird. I didn’t see them in the summer.

In the fall, monarch butterflies begin to make their way to Mexico for a nice, warm winter. 

“In New Jersey, we’re getting towards the tail end. The peak is typically some time in October. It’s really weather dependent. It depends on the wind direction and temperatures. They’ll spend the winter in Mexico and come back in the spring,” said Emily Wilmoth, program director at the Nature Center of Cape May.  

There are generations of monarchs, which means that the monarchs who migrate south aren’t necessarily the ones coming back. 

“They go through multiple generations between their migration. The ones migrating south are a super generation— they live months longer than the other generations. They’ll roost in Mexico in large groups on the trees,” said Emily. 

They don’t have a lot of predators. 

“As caterpillars, the only thing they eat is milkweed. It has toxins in it so it makes them poisonous. That’s how they avoid getting eaten by birds. The bright orange color signals that they taste bad,” said Emily. “As butterflies, they eat the pollen from a variety of nectar plants. As a caterpillar, they are munching on the milkweed leaves.” 

Although the butterflies seem to travel in groups, they’re solo creatures. 

“We see them in large groups because of the timing and weather. When temperatures are getting low, they roost to keep each other warm,” Emily said.  

The monarchs might stop on their way north to lay their eggs. 

“They’ll start the migration back again in the spring. Eggs are being laid between the spring, summer, and fall. It’s a complicated life cycle,” said Emily. 

Monarchs don’t live very long. A few days after they lay their eggs, they die. 

“The typical ones, ones that aren’t migrating down to Mexico usually live for up to six weeks. The ones that make the long migration live for several months, possibly eight to nine months,” Emily said. 

Their journey to becoming a butterfly is quick. 

“Once they lay an egg, it’s several days before it hatches into a caterpillar. From the time they’re a caterpillar until they form a chrysalis takes about two weeks. Once they go inside the chrysalis, it’s about two weeks before it will emerge into a butterfly,” Emily said. 

The monarch butterflies make their way through Cape May for a good reason. 

“Cape May is a migratory hot spot for anything that migrates by flight; It’s a natural funnel. We’re on the tip of a southern facing peninsula. When they get down to Cape May, the Delaware Bay shows up on the other side so they get funneled to the tip of the land mass. In the fall, the prevailing wind direction is northwest. That’s the best for migration; it gives them a tailwind,” said Emily.  

Hundreds and hundreds of butterflies pass through Cape May during the peak of migration season. 

“We had a couple of big pushes here when the conditions aligned and there were large roosts. You can go stand in the dunes and count hundreds of butterflies migrating overhead,” said Emily. 

Researchers learn more about the butterflies’ lifespan and migration patterns through the tagging of butterflies. 

“Tagging the butterflies means that we are putting little stickers on them that have a special alphanumeric code. If that butterfly is resighted or sighted down in Mexico, who sees it can report it. That’s how we learn about the migratory patterns— how long it takes, how long the generations are living.”

These tags don’t have GPS tracking in them and are reliant on monarch watchers reporting the tags, which is then compiled on a map. 

“They’re not GPS units. The Cape May Bird Observatory is putting LifeTags™, little GPS trackers, on the birds who are coming through the area but the technology isn’t quite there yet for the insects. The monarchs weigh as much as a paperclip,” Emily said.  

Anyone can learn to tag butterflies. 

“People are watching for them and tagging the monarchs themselves. Anybody can order tags and do it but we recommend doing your research and doing it correctly. There’s researchers down in Mexico who fly drones over the roost and they’re counting the butterflies,” Emily said. 

Image courtesy of Stef Godfrey