Staggering start to monarch spring migration | News


Migratory monarch butterflies are pouring into Oklahoma these days. They’re not critical, they’re just doing something a little disturbing.

It happens to some degree every year, but some years are worse than others. Persistent cold and late greening this season could make spring 2022 difficult for early migrants of endangered butterfly species now moving north from wintering grounds in Mexico.

“Egg spillage happens when there are too few milkweeds for the situation,” said Chip Taylor, founder and director of Monarch Watch at the University of Kansas.

Milkweed varieties are the only suitable food sources for monarch caterpillars. Ideally, a female will find enough plants to lay one egg per milkweed, over a wide area, for her 100-300 eggs. It’s the ideal survival strategy, Taylor said.

Overall, the monarch spring migration is off to a bit of a rocky start with a combination of cold weather hanging in later and some early migrants already crossing into Oklahoma and Kansas, where milkweed is still in short supply. , did he declare.

International travelers

This first generation of monarchs is the group that flew south from Oklahoma and Texas last fall and wintered in Mexico. In the spring, they fly north and mainly lay eggs in the southern states. The next generation hatches to continue the journey to the northern states and southern Canada.

Sandra Schwinn, Monarch Watch conservation specialist for Oklahoma, said Facebook pages dedicated to butterflies are loaded with photos of people seeing piles of eggs on tiny sprigs of milkweed sticking out of the ground.

“Nobody seems too worried about it right now. The caterpillars are still small,” she said. “In a week or two, some people might feel the crunch.”

Taylor and Schwinn said that while the egg spill situation isn’t always good, nature has ways of coping and people shouldn’t worry too much.

Taylor told a story to explain how the dumping happens.

He said he was talking with a friend and noticed a ragged monarch butterfly with a flea on one wing laying an egg on a small sprig of milkweed nearby.

“She flew away and about 10 minutes later she was back and laying another egg, then she was gone, and again, then again and again. She would fly out and look for more milkweed, then come back when she couldn’t find any,” he said. “She laid seven eggs in a row on one plant, but they don’t lay them all at once, they will look for other plants in the area first.”

Natural uncertainty

Two things make egg dumping a bad thing, Taylor said. The caterpillars will starve to death if they hatch before the plant has time to grow. They could also starve while searching for other milkweeds, he said.

Predators like ants and wasps are the other problem.

“If a predator comes along, it will eat them all,” he said. “If you’re an ant, finding all those eggs in one place is a big problem! »

Much depends on the weather, experts said.

“Some native milkweed plants grow quite quickly and provide plenty of food,” Schwinn said. “I’ve seen plants emerge and flower in two weeks with good temperatures.”

Likewise, caterpillar eggs could wait for good weather — if predators don’t get to them first — Taylor said.

“I once had a situation in Kansas with monarch butterflies that came on April 6 or 7 and there was a lot of egg spillage. The weather was cool and I was able to track some eggs up to 19 days before they hatched,” he said. “Normally they hatch in four or five days.”

Schwinn said flimsy beginnings aren’t unusual for insects, it’s just that with fewer of them these days, it’s getting a bit more ominous.

“Should we be worried this year? I do not know. Time will tell,” she said. “What happens in the summer breeding areas will be as important, if not more important, than what happens here. Each year brings its share of uncertainties.


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