Mid-Atlantic Butterfly Field Forecast for the Week Beginning 2016 Aug 27

Second-generation Delaware Skipper from the Lancaster PA area this week [photo courtesy Tom Raub]

Second-generation Delaware Skipper, one of several seen the same day, from the Lancaster PA area this week [photo courtesy Tom Raub]

This week begins the Season of the Sachem. Every lantana, every zinnia, every Joe Pye weed flowerhead has its golden-brown skippers in attendance, 99 percent of which will turn out to be Sachems. This week the preponderance is overwhelmingly bright orange males; females will turn out over the next week or 10 days in numbers as well.

Other grass skippers are still around, too, if dwarfed in number by Sachems. Fiery Skipper has yet to be seen in any numbers, but Southern Broken-dash is still being seen regularly if only as singletons. Ocola Skippers are well represented by sightings this week, especially the farther south one goes. Crossline, Tawny-edged, Dun, and Swarthy Skippers were few and far between, as was Little Glassywing; Silver-spotted Skippers have already begun to decline from a sizable brood only a week or two ago. The common duskywing in flight at the moment is Wild Indigo, although Horace’s is still around so each duskywing should be inspected. Dion Skippers in some numbers were reported last week and should be watched for in estuarine marshes on pickerel weed where it is blooming. Salt Marsh and Aaron’s Skippers remain on the wing in the coastal marshes.

The most interesting skipper sighting this week is of a local population explosion of Delaware Skippers as a fresh brood in south-central PA. While we normally think of Delawares as single brooded in our area, it is reliably double- or even triple-brooded farther south, and there are records in regional databases of late August and early September specimens still in pretty fresh shape that suggest this species is double-brooded here at least in some years (an irregularity much like Hessel’s Hairstreak that sometimes skips its summer generation in poor years responding to environmental cues we don’t fully understand). This time of year they might be confused if mixed in with fresh, bright male Sachems.

Summer nymphalids are wrapping up; a single Meadow Fritillary made the lists this week, and greater fritillaries are done for until 2017. Searches for female Dianas in the VA and NC mountains turned up empty but did score worn males; veteran observers in the mountains have noted this has been a poor flight year for Great Spangled, Aphrodite, Atlantis and Diana Fritillaries. A couple of Silvery Checkerspot reports have come in, but generally they are scarce in the current generation, and the normal large flight of Pearl Crescents seems to be much reduced this season. Comma and Question Mark were reported across the area, as was a single Mourning Cloak. The latter three should be looked for on windfall apples and pears in old orchards this time of year, along with Red-spotted Purple, Viceroy (if the orchard is near willow), ladies, and Red Admirals. Feeding trays with rotting fruit are also quite productive in late summer and early fall. Buckeye numbers are low but should be laying eggs on gerardia and plantain for a good final brood in late September and October.  Wet woods are still yielding a final generation of Appalachian Brown, and open meadows have the final flight of Common Wood Nymph.

Monarchs were reported by many if not most butterfly observers in the field this past week, including a dozen or more on the National Mall today. Red-banded and Gray Hairstreaks were reported, along with dwindling numbers of Summer Azures. Great Purple Hairstreak was noted in a few locations on the Eastern Shore over the past few weeks, as has Bronze Copper (in DE). American Coppers have not had a good year in the mid-Atlantic and the current flight is no exception.

Among the swallowtail tribe, Black and Spicebush are still flying; the large brood of Eastern Tiger Swallowtails two weeks ago has diminished sharply. Pierid diversity is up, with the best year in the past four or five for Little Yellows. Cloudless Sulphurs were widespread (although in modest numbers) as were Sleepy Oranges.

Butterfly observers should watch carefully over the next two or three weeks for Leonard’s Skipper, as well as for migratory Clouded Skipper and Long-tailed Skipper. Less likely but also possible in the waning summer and early fall are Eufala Skipper and Whirlabout.

This weekend we return to high temps, high humidity and hot sunshine – generally good for butterflies but enervating for butterfly watchers. But should you make it out to winnow through the Sachems for other grass skippers, please report back what you find to us for the next Forecast by commenting here at https://leplog.wordpress.com/ or posting to Google Groups at MDLepsOdes.

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