Mild winters appear to speed annual menu changes for disease-carrying mosquitoes. And the revised biting patterns might play an overlooked role in worsening the risk of brain infections in people and horses.

SALT LAKE CITY — Recent diebacks of aspen trees in the U.S. West may end up increasing the risk posed by a lethal human pathogen, a new study suggests. A tree-killing syndrome called sudden aspen decline that has wiped out swaths of trees across the West in the past decade has also changed the kinds, numbers and interactions of creatures living around the trees, researchers have found — including some carriers of human disease.

Two new fish species — with pancake-flat bodies, wiggling lures on their faces, and elbowed fins for “walking” on the seafloor — have been discovered in the path of spewing Gulf of Mexico oil. One of these pancake batfishes lives in the northern Gulf where oil is already spreading from the Deepwater Horizon blowout.