If you would like to watch the fly emerge in late spring, leave the gall outside through February, since the larva can't complete its life cycle without an extended period of cold. They look like rats, only bigger, fatter, toothier, and slower. Opossums invaded North America from the south about the same time Caucasians invaded it from the east, and both invasions are still in progress. Because opossums evolved in a mild climate, the ones waddling through your headlight beams in the snowbelt from Yankeeland to Colorado are apt to have frost-pruned ears and tails. The opossum is the continent's only marsupial.
Females deliver bee-size young after only twelve and a half days of gestation.
Newborns, essentially mobile embryos, haul themselves up into a kangaroo-style pouch, where they either die or find a nipple that expands in their mouths, buttoning them into place. In one study, a researcher could fit only 21 beans into the brainpan of an opossum skull but needed 150 to fill the brainpan of a raccoon. Several drakes may circle a hen, gurgling, gabbling, and shouting ah, ah, ah or ow-owly, owly, owly. Oldsquaws can dive to 200 feet, deeper than any other duck, and they fly like hurricane-borne shingles. Hunters who have shot oldsquaws as they veered and twisted directly overhead have found pellet holes in their backs.