upper waypoint

This Nasty Parasite Is Ruining Monarch Butterfly Wings

Save ArticleSave Article
Failed to save article

Please try again

Monarchs are locked in a battle with Ophryocystis elektroscirrha (OE), a parasite that can trap a butterfly in its own chrysalis and deform its beautiful wings. Turns out there is a right way, and a *wrong* way, for you to help these butterflies in your backyard.


It’s a magical moment in the life of a monarch butterfly — and a vulnerable one.

Its metamorphosis complete — it breaks free from its chrysalis and pumps fluid from its abdomen into its spectacular new wings.

But for some it’s a struggle.

An old enemy, a parasite called Ophryocystis elektroscirrha, known as OE, is making it harder for monarchs to undergo this crucial transformation.


The infection causes sticky sores on the abdomen, trapping the butterfly inside its own chrysalis.

And by trying to help monarchs, we humans might be making it worse

Each summer, monarchs make their homes in milkweed patches all over North America.

When infected females lay their eggs on the plant, they unknowingly drop microscopic OE spores onto the eggs and surrounding leaves.

A few days later the next generation begins.

The caterpillar goes to work, munching on the empty shell of its old egg.

Then it’s on to the milkweed.

With each bite, the caterpillar downs more and more of these microscopic, football-shaped spores.

Inside the caterpillar’s gut, the spores break open, releasing wormy-looking parasites that burrow out of the gut and into the caterpillars flesh.

When the caterpillar transforms into a chrysalis …

The parasite starts multiplying rapidly, stealing nutrients and taking up space where the monarch would normally grow skin and scales.

When it’s time to emerge, the weakened butterfly fights to free itself from the sticky chrysalis – attracting predators and exhausting itself.

Some never escape.

Others do, but with wings that are all crumpled and deformed … never fully extending.

Or just bent and uneven, making it harder to fly.

Researchers at Emory University in Atlanta take samples of monarch scales to hunt for OE under the microscope.

See all those tiny black specs wedged in between the monarch’s scales?

Those are OE spores

Unfortunately, this one’s infected.

But OE has been around a long time.

So what’s making it such a big problem now?

Well, monarchs have lost much of their summertime milkweed habitat to agriculture and development.

Every stage of their life cycle is connected to this family of unassuming plants.

At the end of summer the local milkweed dies off and the monarchs head south for the winter.

When the plant dies back, it takes the OE down with it.

That’s good.

But, in an effort to help monarchs, some of us plant tropical milkweed in our gardens, with its showy yellow and red flowers.

Tropical milkweed sticks around a lot later into the year than native milkweeds.

That means more time for OE to build up on its leaves

And because the tropical kind doesn’t die back with the rest of the milkweed, some monarchs don’t get the signal to start migrating.

They just hang out on the infested plants, missing their chance to hook up with all the other butterflies that spend their winters partying down south.

What’s worse, they spread OE to healthy butterflies that pass through on their migration.

So, if you wanna help the monarchs –- do ’em a solid!

Cut back your tropical milkweed in the fall.

And the next time you plant milkweed … make sure it’s a native kind.

With all the problems that monarchs face, this is one small thing we can do to help.

Hey Deep Peeps!

Ever wished you were invisible?

The glasswing butterfly knows just how to do it.

And why, exactly, is the very hungry caterpillar so dang hungry?

Well, because it has to stock up on protein before its face falls off.

You know how it is.

Enjoy, and see ya next time.

lower waypoint
next waypoint
More Hot Weather Is Coming to the Bay Area. Here’s How Long It Will LastCalifornia Has a New State Park, and It Is Now OpenCalifornia Shows Where Insurers Would Need to Boost Coverage in Fire-Prone AreasSan Francisco's Aging Infrastructure Ill-Prepared for Future Flooding, Report WarnsCalifornia’s New 1600-Acre State Park Set to Open This WeekCalifornia Researchers Develop Board Game to Teach Wildfire Safety. Can It Save Lives?What to Know About Landmark Wildfire Bills Led by California CongressmanSchizophrenia: What It's Like to Hear VoicesEver Wake Up Frozen in the Middle of the Night, With a Shadowy Figure in the Room?Everything You Never Wanted to Know About Snail Sex