Date: 09/19/2001

Number: 150

We are in the midst of one of the big pushes for sure. Today, at home (Nellysford, VA) and at Sweet Briar College, there is a big peak of monarchs nectaring on Buddleas, Solidago, and various cultivated asters in our butterfly gardens. Sunday 16 September, the monarchs began building up, nectaring on goldenrods, Buddleia, and various asters in my garden. On Monday 17 September there were more, Tuesday more still, and today there are at least 150 in the garden. All monarchs--except for a few old laggards--are very fresh and in mint condition, which indicates we are now have shifted into the migratory phase.

The butterflies are very skittish, and one patch of goldenrod had at least 50 on the flowers, and all flew up when a cloud passed over. This reminded me of the behavioral response to clouds in the Mexican overwintering colonies that we described a couple of years ago (in: W. H. Calvert, L. P. Brower, and R. O. Lawton. 1992. Mass flight response of overwintering monarch butterflies (Nymphalidae) to cloud-induced changes in solar radiation intensity in Mexico. Journal of the Lepidopterists' Society 46:97-105.).

I also checked a field site that I monitor in Nellysford, VA Monday afternoon (4:12PM, 17 September 2001). Ten days ago there were 2 monarchs in the field. Monday I counted 17 on a species of yellow daisey, and 32 more in the same field on the lovely orange flowers of "butterfly weed", Asclepias tuberosa. (This is very late for tuberosa flowers, but the farmer mowed the field about 6 weeks ago and the milkweed shoots resprouted, hence the new blooms.)

We have also been monitoring our Buddleia garden at Sweet Briar College, and the same temporal build up has and is occurring.

It will be interesting to see how the Atlantic costal migration is proceeding (Denise Gibbs is monitoring for with us at Chincoteague on the coast and Dick Walton and at Cape May, NJ).

Nellysford, VA

Latitude: 37.8 Longitude: -79

Observed by: Lincoln
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