WINTER WONDERS

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If you find a mouse hole in the snow, take note of its location and come back in the spring. Part the grass, and youll discover an elaborate maze of pathways pummeled smooth by countless wee footsteps.

Some Gall!

As you venture across winter fields, watch for the tall, dried stalks of goldenrod, one of North Americas most widespread weeds. Chances are youll spy at least one stalk with an odd round swelling about an inch in diameter: a gall formed around an invading insect. Using a pocket knife, carefully cut open one of the swellings. Inside, youll discover a hard, pale worm, probably the larva of a goldenrod gall fly.

In late spring and early summer, adult gall flies??which are less than a quarter inch long, have clear black-banded wings and prefer walking to flying??lay eggs on the tips of emerging goldenrod stems. About 10 days later, the eggs produce larvae that bore into the stems??usually one larva per stem. The little worms chewing action and saliva stimulate the growth of extra plant tissue around it, creating a pithy, vegetative sphere that provides both shelter and food. In autumn, before going into dormancy, the larva burrows outward, preparing an exit tunnel that stops just short of breaking through the galls surface. Then the larva retreats back to the galls center, where it remains until it pupates and turns into an adult fly the following spring.

If you remove the larva and warm the immobile creature in your hand for a minute or two, itll come out of its cold-weather stupor and wiggle. No wonder winter anglers like finding goldenrod galls: live bait! Downy woodpeckers are fond of goldenrod galls, too, and use their tiny, pointed bills to bore into the spheres to extract the morsels inside.

Amazing Snowflakes

Look upward as snowflakes drift delicately from the sky. Go ahead and stick out your tongue??can you catch one?

Aristotle had it almost right when he wrote, When a cloud freezes, there is snow. A snow crystal is born when a water droplet condenses and freezes around a bit of dust or ice inside a cold cloud. The infant crystal, a few thousand water molecules held by electrical charge in the shape of a six-sided plate or disc, immediately begins to fall. Its the start of a two- to six-mile tumble to earth, a journey that may take some two hours and perhaps cover hundreds of horizontal miles.

As the crystal tumbles, it grows by drawing trillions of vapor molecules out of the air and onto its surface like a magnet. The molecules flow across the crystal and freeze, locking together in any of the myriad patterns that we associate with snowflakes. But the atmosphere is a turbulent place, and a snow crystal is a delicate wanderer. With each small variation in air temperature, with each flutter of wind, the crystal changes shape. A hexagonal plate may sprout fernlike projections; a star may suddenly lose its points. Or the crystal may collide with others and shatter, seeding the air with particles around which more snow forms.

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