Pawnee and Western Branded Skippers – Big Year Species 100 and 101

This past Saturday (Aug 22) Jonathan Nikkila and I made a late summer trip (an annual for me, Jon’s first) to Ash Hollow State Historical Park at the west end of Lake McConaughy in Garden County to look for skippers and swallowtail larvae. There was a high haze all day which the evening weather said was smoke from the Colorado forest fires. We started out looking on gayfeather (Liatris sp.) flowers on a west facing slope near the visitor’s center about 9:30 am MDT with temps around 70 degrees F. There wasn’t much activity there so we crossed the highway to Windlass Hill which had some east facing slopes in hopes that that area would be a little more productive. We had hiked about 2/3 the way up the hill on the appointed path (so as to have an unobstructed view of any rattlesnakes we might intrude upon) without any action there either. I was beginning to get the sense of deja vu from my trip into the loess hills south of North Platte two days prior when I was shut out. Then the butterfly gods snapped their fingers and all of a sudden there were skippers everywhere. The first one we got a “good, but not that good” look at I think was a Delaware Skipper (Anatrytone logan) but we captured the next and determined it to be a Pawnee Skipper (Hesperia leonardus pawnee) which was quickly followed by several others. After hiking the rest of the way to the top of the hill (and crossing a depression in the hilltop caused by the ruts of wagons following the Oregon trail) we started back down and encountered a Western Branded Skipper (Hesperia colorado ssp). All told we probably saw over 20 Pawnee Skippers but only 1 or 2 Western Branded Skippers which is normal for that area.

Pawnee Skipper – Three subspecies of this skipper inhabit eastern North America west into Colorado, Wyoming and Montana. All fly in late summer and in Nebraska the subspecies (H. l. pawnee) is found mainly in undisturbed prairies in the western half of the state. Larvae feed on various prairie grasses including little bluestem (Andropogon scoparius) and Gramma grasses (Bouteloua sp.). Males and females are dimorphic (different in appearance) dorsally. The ventral hindwing may range from uniformly gold to having a faint band of spots. Adults are fond of gayfeather (Liatris sp) flowers.

Western Branded Skipper – Twelve subspecies of this skipper inhabit the western United States including three (colorado, ochracea and oroplata) from Colorado. Which subspecies our populations fall into concerns me not a whit. Heck, maybe even another new subspecies – why not. The point being it is quite variable across its range (which taxonomists love). The species ranges east into the Dakotas, Nebraska and Kansas. In Nebraska it has been found westward from from the Niobrara Valley Preserve (Keya Paha and Brown counties) in the north to Dundy county in the southwest and flies in a single brood in late summer. Larvae feed on various grasses including needlegrasses (Stipa sp.) and bluestems (Andrpogon sp.). As with the the other Hesperia species the sexes are dimorphic. This skipper is a NENHP Tier 2 species (see June 14 post).

Clio Tiger Moth – While stalking skippers to photograph Jon noticed an interesting tiger moth I’d never seen before. We think it’s a Clio Tiger moth (Ectypia clio). It’s primarily southwestern (US) in distribution and its larvae (which are black) feed on milkweeds. In Nebraska it is restricted to the panhandle region.

Another reason for my annual trips to Ash Hollow is to check on the size and abundance of Two tailed Swallowtail larvae which feed on chokecherry and ash, both of which are abundant in the area. If they are large and numerous I take a few home to rear. This year I looked for about an hour in the morning and found only one small one. It would have taken two to three weeks and several molts to get it to the pupal stage. A lot can go wrong in that time under my care (or lack thereof) so I left him to his fend for himself. In their early stages (instars) the larvae resemble bird droppings. Note the “silk” pad the larvae spins on the leaf to give itself something to hold onto when the wind blows.

Ash Hollow State Historical Park is one of several places in Nebraska where the ruts of wagons following the Oregon Trail are still visible. This is where they dropped down into the North Platte River valley to follow it west to near Casper, Wyoming. For more information on the park visit the Nebraska Game and Parks website http://outdoornebraska.gov/ashhollow/

So after nearly a month being stuck on 99 Nebraska Big Year species I finally cracked 100 species (101 YTD), something I thought this spring would be a really good year. The adventure continues with my new goal being 105 species.

Continue sending your photos to NebraskaButterflies@gmail.com and we’ll do our best to get them posted on our images page. Thanks for your time and interest!!

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