31.0°

Three (and a half) sunny days in a row! In Juneau? In October? Better not squander them!

Day 1

We spent the morning peering at the rock faces near Nugget Falls. That may sound a bit strange, but biologists are sometimes that way. We were searching for a special insect that has been found only in this particular area. This new species was discovered a few years ago by visiting entomologists and its occurrence was later confirmed by a local expert. That local expert was with us on our search, and because he knew what to look for, the search was successful.

What is this special insect? It's a caddisfly, and most species have aquatic larvae. Mature larvae turn into flying adults that mate briefly and lay eggs for the next generation. This caddisfly larva is tiny, about a quarter of an inch long, so it is not easy to spot until you've been shown a few examples. It lives in a protective tubular case of tiny sand grains held together by silk. Each larva puts a delicate frill of moss around the opening of the case; the effect is beautiful under magnification. The larva can poke its front end out of the case, use its legs to crawl around (dragging its case along), and search for the microscopic algae that it eats.

This caddisfly occurs in a very special habitat: not the falls itself, not the thick mats of algae and moss alongside the falls, but on the smooth, moist rock surfaces that look as if they are bare-until you look closely and see small, dark, elongate shapes on the wet surface and perhaps feel the slippery film of micro-algae.

Day 2

The next day was sunny too, but the wind was gusting mightily, twisting the treetops and raising dust clouds near the Eaglecrest lodge. The air temperature was decidedly crispy, but we headed up to Cropley Lake which had been whipped by the wind into whitecaps. Vibrant splashes of red marked the position of now-leafless native mountain ash shrubs, whose fruits stay edible (to birds at least) for months.

The surface of the small ponds in the subalpine meadows was firmly frozen, with lovely, feathery patterns in the ice that cast intriguing shadows on the bottom. Looking through the ice, we could spot a few water boatmen still zipping around. These water bugs swim using their big hind legs as oars. Lacking gills, they actually breathe air, so they have to go the surface to breathe, and they may capture a bubble of air to carry with them under water. Most water boatmen suck on the juices of plants, but some are predatory, sucking the juices out of small aquatic animals. Adults and immatures look very similar when in the water, but the adults have wings and eventually fly, dispersing to other, sometimes very distant, ponds to lay eggs. Apparently, some species can overwinter as adults. It seems that very little is known about the particular species that live in our area, so there is much to be learned.

Day 3

This beautiful day was distinguished by a circumnavigation of Naked Man Lake above Eaglecrest and by two (yes!) kinds of birthday cake at lunch. It took some searching to find a nice sunny spot that was also out of the increasingly cold wind. A clump of dense mountain hemlocks at our backs finally did the job.

There were lots of "frost fingers" along the trails. I don't know the proper name for these clusters of columnar ice that look as if they have been forcibly extruded from the freezing mud. Some of them are perfectly straight, but others curl, and some even achieve a full curl. I would love to know how these formations come to be.

And that half-day?

Well, I got some yard work done, and it looks like the rest of the job will be done in the rain. But you never know - this has been a surprising October.

• Mary F. Willson is a retired professor of ecology.