Out in the fields, each swollen goldenrod gall contains a tiny moth or fly waiting to emerge in spring. A decomposing log on the forest floor not only is soft enough to permit entry, but its bacterial decay creates warmth that comforts as it provides safe haven for insects, spiders, centipedes, millipedes, worms, and snails. Such creatures also find protection in forest soil, an earthen incubator warmer than soil in open meadows where the frost line plunges three or four feet deep in our north country. A covering blanket of forest leaf litter alone, with its labyrinth of insulating air spaces and frosty cover, provides winter shelter for a wide array of small active creatures. A few insects are true denizens of winter.
Snow fleas assemble at the base of a tree where warmth creates melt-water on a sunny day.
Hordes of these tiny primitive springtails may blacken sunken patches of snow, such as footprints and tire tracks. Micro-algae and decaying plant material constitute their staple food. One kind of snow flea eats smaller springtails, but when the sap rises late in winter, most species congregate near outbreaks of the sweet flow. In early winter, I may discover scorpion fly larvae and pupae around the base of a tree trunk, or in leaf litter. Wingless, with a long pointed head, a scorpion fly looks like no other fly we're familiar with.