The green of the ice and water begins to be visible about half an hour before sunset.

January 20. 

A second remarkably pleasant day like the last. 

P. M. — Up river. 

I see a large white oak perfectly bare. 

Among four or five pickerel in a “well” on the river, I see one with distinct transverse bars as I look down on its back, — not quite across the back, but plain as they spring from the side of the back, — while all the others are uniformly dark above. Is not the former Esox fasciatus? There is no marked difference when I look at them on their sides. 

I see in various places on the ice and snow, this very warm and pleasant afternoon, a kind of mosquito perhaps, a feeble flyer, commonly resting on the ice.

The green of the ice and water begins to be visible about half an hour before sunset. Is it produced by the reflected blue of the sky mingling with the yellow or pink of the setting sun?

What a singular element is this water! I go shaking the river from side to side at each step, as I see by its motion at the few holes. 

I learn from J. Farmer that he saw to-day in his wood lot, on removing the bark of a dead white pine, an immense quantity of mosquitoes, moving but little, in a cavity between the bark and the wood made probably by some other insect. These were probably like mine. 

There were also wasps and what he calls lightning-bugs there.

H. D. Thoreau, Journal, January 20, 1859

Among four or five pickerel I see one with distinct transverse bars as I look down on its back, — while all the others are uniformly dark above.  See April 6, 1858 (“ I asked him to let me see the fish he had caught. It was a little pickerel five inches long, and appeared to me strange, being transversely barred, and reminded me of the Wrentham pond pickerel; but I could not remember surely whether this was the rule or the exception; but when I got home I found that this was the one which Storer does not name nor describe, but only had heard of. Is it not the brook pickerel?”); April 18, 1858 ("I saw in those ditches many small pickerel, landlocked, which appeared to be transversely barred!”); May 27, 1858 ("De Kay describes the Esox fasciatus, which is apparently mine of May 11th.”); May 11, 1858 ("Thickly barred transversely with broken dark greenish brown lines, alternating with golden ones. The back was the dark greenish brown with a pale-brown dorsal line.”); See also Proceedings of the Boston Society of Natural History ("[Mr. Putnam] exhibited specimens of the young and adult pickerel, to show that the "short-nosed pickerel " is specifically distinct from the "long-nosed " — the Esox reticulatus — and said that the " short-nosed " species is the Esox fasciatus of Dekay, which is not the young of the Esox reticulates”)  See also A Book of the Seasons, by Henry Thoreau, Pickerel

The green of the ice and water begins to be visible about half an hour before sunset. See January 7, 1856 (“Returning, just before sunset, the few little patches of ice look green as I go from the sun (which is in clouds). It is probably a constant phenomenon in cold weather when the ground is covered with snow and the sun is low, morning or evening, and you are looking from it.”); December 25, 1858 (“The sun getting low now, say at 3.30, I see the ice green, southeast.”); February 12, 1860 ("Returning just before sunset, I see the ice beginning to be green...”)

The green of the ice

begins to be visible

just before sunset.

January 20, 1859

What a singular element is this water! See March 14, 1860 ("No sooner has the ice of Walden melted than the wind begins to play in dark ripples over the surface of the virgin water. Ice dissolved is the next moment as perfect water as if melted a million years.”)