Date: 08/24/2013

Number: 4

On 24 August 2013, Lincoln Brower, Dan Slayback and Linda Fink visited Big Meadows in Shenandoah National, Park, VA. The weather was mostly bright cloudy with occasional sun and around 65 degrees when the sun was not out. We arrived at the picnic area around 12:30 PM and saw no monarch adults and saw no evidence of larvae eating on the milkweeds. Between 1:40 and 2:35 we walked around in the Big Meadow open area which had numerous A. syriaca plants growing in patches in the field. Most of the plants were past bloom or in early to mid pod, but there were also a few in fresh flower. We searched the field for eggs, larvae and adults. Because it was cool while overcast most of the time, we did not see many butterflies flying and saw 0 monarch adults. We found three syriaca plants with larvae. The first plant had two early 2nd instar larvae on the upper side of apical leaves. We also found one mid-fifth instar on a second, non-flowering syriaca. No eating had occurred on the plant so the larvae had to have crawled onto it from another nearby plant (as described by Su Borkin in WI). We then found an early 4th instar larva feeding in a syriaca flower head. No more larvae or eggs were found and no evidence of further monarch larval eating was seen. Had there been an abundance of monarch adults in the field, it was warm enough that we would have set them to flight. The presence of 2nd, 4th and 5th instar larvae in the field indicates they were almost certainly the offspring of three separate females and supports the hypothesis of at least a partial overlapping of generations. Knowing the general paucity of monarchs reported this summer so far, we were not surprised by our meager findings of only four larvae. Both sides of the 50 mile drive along the parkway from the south to the Visitor Center had an abundance of milkweeds, mostly syriaca but also exaltata. Many of these milkweeds were in good condition. It was partly cloudy going north and mostly sunny heading back south, and we saw 0 monarch adults while driving the 100 mile round trip..

On 13 September 2007, Lincoln Brower visited the same area. The picnic area in the main visitor center area had hundreds of Asclepias syraiaca plants growing beneath the understory forest. Asclepias exaltata was also present in the understory. Monarch larvae through the fifth instar were extremely abundant and numerous chrysalids had formed and many 5th instar larvae had spun up under the eaves of the restroom doors.

Shenandoah National Park, VA

Latitude: 38.5 Longitude: -78.4

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