Marching Up the Map

May 10, 2018 by Elizabeth Howard

Here they come! The migration entered 6 new states this week and our first Canadian province.

“Yay!! An adult female laying eggs. She was in the same location as my first last year, one year and a week later.” Kim Frey, May 5, 2018, Lititz, PA

Look at Them Go!

The migration’s leading edge advanced 255 miles during the past week as it entered 6 new states and the 1st Canadian province. First-of-year sightings were reported from Nebraska, Iowa, Michigan, South Dakota, Pennsylvania, New York, and Ontario.

The northernmost monarch now stands at latitude 44°N where a surprise sighting from South Dakota was reported on May 8th. If that monarch came from Mexico it would have traveled 1,800 miles.

Overlapping Generations

People are now reporting faded - and fresh - butterflies. Monarchs of the overwintering generation whose wings are showing a lot of wear and tear are overlapping with fresh, first-generation butterflies.

“We have seen 1st generation monarchs all weekend at multiple locations around us. We have also observed a number of remigrants still in our area or possibly new ones passing through. They are weathered and worn and noticeably different in flight than the fresh new generation monarchs,” wrote Chuck Patterson from Driftwood, TX on May 6th.

Interestingly, based on comments and images, many of the northernmost monarchs do not appear to be 1st generation. Worn-winged butterflies were reported in Philadelphia, PA, Cape May, NJ  and Litizt, PA.

Population Building

The number of sightings doubled this week compared to last. Watch for sightings to surge as more and more 1st generation butterflies emerge. The population always swells during the 2nd half of May.

Watch Out for Look-Alikes

As the spring season progresses, many different species butterflies are emerging. Can you distinguish a monarch from other look-alike butterflies?

Butterfly Identification