Monarch Migration News: May 28, 2015
By Elizabeth Howard
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Fresh, new butterflies — children of the monarchs from Mexico — surged northward last week. The number of eggs reported brings a hopeful start to the summer breeding season.

Monarch Butterflies at Sanctuary in Mexico
Donna Lorello

News: Northern Breeding Begins
A sudden wave of migrants spread into Iowa, Minnesota, Wisconsin, Illinois, Indiana, Michigan and Ontario between May 16 and 25th. The northernmost monarch now stands at latitude 47°N. Two sightings reported from Ontario were the first for Canada.

These monarchs are the children of those that overwintered in Mexico. The eggs they are laying will be the grandchildren.

Finding 1st Eggs
Egg reports increased too in the upper Midwest as the butterflies got down to the business of breeding. Among those who saw their 1st eggs were schoolchildren in Urbandale, Iowa.

"After a chilly week it got to the mid 70s today. After school we found 19 eggs on our common milkweed!" May 22, 2015 Urbandale, IA

Compare Years
These maps compare 1st egg reports from 2009-2015. So far, this year's production is lower than in many previous years. Possible causes include:

  • a late start to the breeding season in the south
  • low reproductive success in the south
  • a delayed arrival in the north
  • cool spring temperatures

Egg-laying Preferences
Obervers are submitting pictures that show various parts of the milkweed plant where monarchs lay eggs. Explore the images and consider ways oviposition selection could be related to offspring survival.

Rates of Survival
Fewer than 10% of eggs laid survive past the first instar caterpillar stage, and predation is the main cause of mortality, according Dr. Oberhauser's research. Volunteers can assess the rate of monarch survival in the milkweed patch by counting eggs and larvae.

Monarch Larva Monitoring Project

Looking Ahead
Watch for reports of monarchs and eggs in the east this week. A strong high pressure cell is parked off the Atlantic coast and causing persistent south winds in the eastern states and Canada. Let's see if monarchs take the free ride northward!

Monarch Butterfly Migration Maps
1st Eggs
Monarch Butterfly Egg on Milkweed Bud
On Bud
Jody Vernay
Monarch Butterfly Egg Under Milkweed Leaf
Under Leaf
Harriet McCarthy 
Monarch Butterfly Egg Near Tip of Milkweed Plant
Near Tender Tip
Sue Fox McGovern
Conservation News

Radio Interview: PRI's The World
'The situation is desperate' for monarch butterflies, but here's the plan to save them.

How you can help Monarch Butterflies at Sanctuary in Mexico
Maps: Report Your Sightings
Monarch butterfly migration map Monarch butterfly migration map Map of milkweed emergence: Spring 2015
What to Report First Adult
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Monarch butterfly migration map Monarch butterfly migration map Monarch butterfly migration map
First Egg
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First Larvae
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Other Observations
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Journal and Activities
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Next Update June 4, 2015