One of the surest signs of a warmer-than-usual winter is the appearance of vast congregations of pinhead-sized "insects" on the kitchen porch railing both day and night. I put insects in quotes because these six-legged invertebrates are no longer considered to belong to that Class of creatures and may, depending on which expert you consult, be in a Class of their own. True, the Collembola, as these diminutive hexapods are known to systematists, have six legs, but, unlike insects, they have internal mouthparts and a spring-like mechanism tucked under their abdomens that enables them to leap great distances and spring out of harm's way, hence, their common name, "springtails." Collembola are exceedingly common in the leaf litter and soil, but they're most noticed when too much moisture pushes them upwards, sometimes on top of the snow or, in this case, to the top of the porch railing for a warmish weather get-together and jumping competition.