Monarch Butterfly Update: May 26, 2011
Please Report
Your Sightings!

The migration continued to advance during the past week—slowly, steadily, and a little early. We're still waiting for the big surge in numbers to occur. Is the drought in Texas affecting timing this spring? Did drought drive the monarchs out of Texas early? Explore how data citizen scientists are collecting helps answer key questions like these. Finally, take a close-up look at some amazing adaptations: larvae legs!

This Week's Update Includes:

Image of the Week

Photo Gallery: Butterfly Eggs

Hooked on Milkweed

News: Fresh-Winged Monarchs!

Visiting the state capital in Minnesota, flying across home plate on a baseball field in Iowa, and laying eggs on milkweed in Wisconsin. A new generation of monarchs is appearing to the delight of the people who see them.

"The female was in good shape, undoubtedly the first new generation," Mr. Swerkstrom said. He snapped this picture of a newly-laid egg on a milkweed in Wisconsin.

Grandchildren on the Way
About one month from now, in late June, this Wisconsin egg will become an adult butterfly. It will be the second generation of monarchs produced this season, and a grandchild of monarchs that overwintered in Mexico.

Counting Generations
Over the summer, at least two more monarch generations will be produced in the north. It typically takes about one month for each generation to develop. This means that:

  • the great-grandchildren will appear in late July,
  • the great-great-grandchildren will appear in late August—and these are the butterflies that will migrate to Mexico!

Sightings per Week
Now that the first spring generation is on the wing, we've been waiting for sightings to soar. We should see nearly double the number of sightings per week. (See graph.) When will it happen?

Cool Temperatures, Slow Monarchs
Spring has been cold and rainy in the north. Last week, an observer in Ohio witnessed how cool conditions can affect monarchs:

"I was walking in the yard and looked down and saw a female monarch laying in the grass. I thought she was dead, but saw a bit of movement. I think she was just COLD! It's in the mid-50s and rainy. I brought her in to warm her up and now she's spreading her wings instead of laying on her side. The milkweed is barely up, so I hope she can find a suitable plant for laying her eggs."

Temperatures were much colder this week than last week.
Grandchildren on the Way





Sightings reported per week, spring 2011 migration
Sightings per Week

No big increase yet!


YOUR Observations are Important!
Please report the first monarch you see this season. Even if others have already reported from your region, your observation is valuable.
Spotlight: Drought in Texas

"We are in the seventh month of drought, the worst since 1950-1957, the worst on record for some regions of Texas," wrote Harlen Aschen from Port Lavaca, Texas.

"I read that Monarchs lay fewer eggs in hot, dry areas. Is it safe to assume that the reason we aren't seeing near as many butterflies as we usually do at this time is because of our extreme drought?" asked a woman in Houston, Texas.

How is the drought in Texas affecting monarch habitat? These images tell the story. Compare conditions last spring to this spring at Cibolo Nature Center in Boerne, Texas. Kip Kiphart and team monitor this habitat as part of the Monarch Larva Monitoring Project. He notes:

"There are and have been very few nectar plants. There was abundant milkweed but not much monarch activity, possibly related to a lack of nectar sources. The milkweed (Asclepias asperula) came up early and is senescing early. Over a quarter of the 200 milkweeds we counted on May 7th were brown and will disappear in the next couple of weeks. Pretty pathetic."

How Important is Texas?
The drought in Texas could be impacting the number of monarchs we are seeing now. Here's why: When monarchs moved into Texas this spring they found the state gripped by drought. (See drought map.) This lack of rainfall meant fewer flowers to feed adult butterflies, and fewer milkweeds for females to use as host plants. As this pie chart shows, Texas is the state where most early spring monarchs are sighted. This means spring breeding habitat in Texas is important for first generation production.

How Does This Spring Compare?
This bar graph compares Texas sightings this spring to past years. Notice: only 35% of this spring's sightings were from Texas, compared to 65% last spring.

  • Did drought conditions drive the migration out of Texas early this spring, and into other states?
  • Is it taking longer than usual for the first spring generation to develop because the monarchs are growing in states where conditions are cooler than in Texas?

Citizen Scientists Are Helping
Notice how data citizen scientists are collecting helps answer key questions about the monarch population.

  • Volunteers Are Needed: Find out how you can monitor your local habitat this breeding season as part of Dr. Karen Oberhauser's Monarch Larva Monitoring Project.
Drought in Texas
Drought in Texas

Temperatures were much colder this week than last week.
Drought Map


Pie chart: spring sightings by state

State-by-State Comparison


Texas sightings as percent of total early spring sightings.

Year-to-Year Comparison



Slideshow: Amazing Adaptations! Larvae Legs

Crawling along a paper-thin leaf. Eating while hanging upside down. Monarch caterpillars defy gravity. Through close-up images of the monarch larva's legs, students explore adaptations that help monarchs survive on a milkweed plant.

Essential Question:
How do the monarch larva's legs help it survive?

The Migration: Maps and Journal Page
Pre-migration map: Winter monarch butterfly sightings (January or February) Map of milkweed emergence: Spring 2011 Journal Page
How do the monarch larva's legs help it survive?

Let's find out when and where monarchs and milkweed appear this spring.

Annual Evaluation: Please Share Your Thoughts

Please take a few minutes to complete our Annual Evaluation. With your help, we can document Journey North's reach, impact and value. Thank you!

The next Monarch Migration Update will be posted on June 3, 2011.