Date: 06/06/2010

Number: 1

I was in MN over the weekend for a family function and decided to conduct a mini survey for monarch eggs and larvae on the drive back to KS.

Much of the area to the south of the Twin Cities is intensely farmed and the road margins are narrow and mostly filled with grass.
Milkweed patches were scarce and we only spotted 8 along dirt roads in over two hours of driving from Rosemount to Fairbault, with one in Albert Lea. I couldn't reach one patch due to water in the ditch but of the other 7 - 5 had eggs and larvae - one patch with only one egg.
Of the four others, 30-80% of the plants showed damage from feeding by larvae. All of these patches were small (<30 ramets of common
milkweed) and the most productive ones were right at the margin of the gravel and the adjoining vegetation where predator populations were low. In two of these sites it wasn't uncommon to find 2-3 larvae per plant. Eggs were not common - roughly 20% of the number of larvae. The larvae ranged in size from newly emerged first instars to terminal 3rd instars.

These numbers sound good but when milkweed is scarce and particularly when you find it growing on the road margins where predator numbers are often low, finding numerous eggs and larvae just after a wave of monarchs has moved through is not unprecedented and it doesn't tell us much about the population except that a good number of monarchs moved through.

Similar observations were recorded along KS roadsides in the spring of 2000. It looked like the population was off to a great start but in December only 2.83 hectares were occupied by monarchs in all of the overwintering sites in Mexico. (Reported with images in the 1999 Season Summary).

Courtesy of Monarch Watch

Albert Lea, MN

Latitude: 43.7 Longitude: -93.4

Observed by:
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