City Creek Nature Notes – Salt Lake City

October 21, 2016

October 21st

Smart Trout

1:30 p.m. At the water striders’ pool at picnic site 5 (Sept. 12th), I see the first brown trout in the canyon for over a month. The light filtering through the trees brings out the molted spotting on its upper skin. This trout hides in the pool under a branch that dips across the pool’s middle. I remain motionless for a minute and in reply it station-keeps with one eye gazing at me. When I make a sudden move by taking one quick step the right, the trout frantically swims under a stream-cut overhang that is covered by dense foliage. It has excellent eyesight even through the water’s surface. In one corner of the pool is a single water strider, and these are what the trout has been feeding on. Later, the trout is joined by two smaller companions.

Today, the yellow tube of falling leaves (Oct. 11th) is over and temperatures have risen into the sixties. The predominate colors between mile 0.0. and mile 2.0 is brown and grey. Like the last sunflower (October 14th), this is another marker of seasonal Fall change. Because of the temperature, insects have again become active, but I count only thirty on the road, including possibly two Yellow-head bumble bees with black rumps, a Variegated Meadowhawk dragonfly, a large unidentified blue dragonfly, and, in the box at picnic site 11, a sole European Paper Wasp (see Oct. 11th). These rare late season insects are now more visually striking; they provide the only accents of bright colors now that the leaves have fallen. Crickets are still heard in meadows and forest undergrowth and some have come to die on the road. At picnic site 12, a woodpecker can be heard but not seen. Common woodpeckers in the canyon that drum on trees are the Downy Woodpecker (Picoides pubescens) and the Northern Flicker.

Together, they will swim upstream to join their mates at a shallow fifteen by twenty foot pool below an outdated flood gate at mile 2.8. A regulatory “no fishing” sign on the sluice box protects them from humans. During the winter, ten or fifteen trout can be found there, resting in water so cold that it would kill a person in two or three minutes.The next marker of the seasons, as winter storms reappear at the beginning of November and December, will be season’s end for the flying insects, season’s end of the crickets, and the falling of the last remaining leaves during a heavy snow storm.


October 13, 2016

October 13th

The Moth Who Wore Pink Pants

6:00 p.m. The overnight cold leaves faltering insects on the road, and this aids in identifying flying insects that are otherwise too fast to see or too uncooperative to pose for a portrait. In the last few days, four have landed on the road.

The Pepper-and-Salt Moth (Biston betularia) is an example of evolutionary camouflage. Whether on the road or on a tree trunk, as its name implies, the salt-and-pepper grey pattern on this wings blends in perfectly with the varied grey backgrounds of tree trunks. Darwin famously pointed to this moth’s cousin, the European Peppered Moth, as an example of artificial selection: As surfaces turned black under the coal of the first Industrial Revolution, the wings of British peppered moths turned black in order to match their sooty surroundings. More recently and following the clearing of the skies in our post-Industrial Revolution era, Richard Fox of the British Garden Moths Count Project reported that these black British peppered moths have re-evolved to their original peppered appearance.

A couple of days ago, when I try to take a close picture of the Pepper-and-Salt moth on the road, it is startled and vigorously flaps its wings. Underneath its wings, its thorax or abdomen is painted bright pink with white stripes. At best, I can obtain only a blurred picture of the agitated moth with its pink pants. I check my insect guides and find no mention of the pink undergarments.

A Western Yellowjacket wasp (Vespula penslvanica) was also trapped by cold on the road. It can be distinguished from the paper wasps seen on October 9th by their more stout bodies, hairier thoraxes, and their generally more bee-like appearance. This wasp has a red-brown color to its abdominal segments rather than the typical black. It has probably been displaced here by a recent field-clearing project of the Utah Conservation Corps.

This afternoon, there are two more insect refugees on the road. At mile 1.6, the first refugee is a wasp with a dark red-brown head and thorax. The upper one-third of the abdomen is also dark brown, before it turns to alternating yellow-black bands. I am unable to find it in any guides, and this wasp is unidentified. Further down canyon, another wild bee variant is found. The lower third of its abdomen is black, while the upper third is alternating black and red-orange. It is similar too but not the same as the red-rumped central bumble bee, first seen on September 24th. The red-rumped central bumble bee has a red, not a black rump. It could be the Yellow-head bumble bee (Bombus flavifrons), but it is too late in the year for them to be out.

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