Monarch caterpillar surveys, July-August 1982-2022, in a Milwaukee greenspace approximately 200 feet wide x 800 feet long
This greenspace in the City of Milwaukee existed prior to 1980. Plants growing there included common milkweed, whorled milkweed, brome grass, bluegrass, timothy, sweet clovers, purple clover, common yarrow, gray-headed coneflower, chicory, field bindweed, thistles, ox-eye daisy, birdsfoot trefoil, vetch, wild bergamot, Ohio spiderwort, Indian grass, asters, goldenrods, river grape, buckthorn, ash, walnut and others.
Counts of common milkweed plants were made in June of each year. Surveys of monarch caterpillars were made weekly from the second week in July through the end of August. The greatest number of caterpillars counted in a day are logged in the following table, along with the number of common milkweed plants counted in June.
Year, most caterpillars seen in a day, June count of common milkweed plants
1982, 12, -
1984, 8, -
1987, 7, 286
1988, 5, 267
1990, 10, 310
1994, 7, 325
1998, 14, -
2000, 11 , -
2004, 10, -
2005, 4, -
2008, 5, 382
2012, 4, -
2013, 1, 415
2014, 0, 349
2015, 0, 347
2017, 2, 469
Comments, 2017 Greenspace was completely mowed June 15, and again on July 18 by City of Milwaukee crews. Two small caterpillars seen on July 17, on common milkweed near the fence. One monarch was laying eggs on a common milkweed plant by the fence on July 17.
2018-2021, 0, -
2022, 0, 29
Comments: Greenspace has had paths mowed through it in June each year from 2018-2022. It is completely mowed in late August each year. Much of the area is now covered by teasel, Dipsacus fullonum (D. sylvestris), which was brought in in 2005, apparently on the large mowers that were used to cut down the plants in late August to early September.
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