Lasiurus ega
southern yellow bat

Lasiurus ega is widely distributed from Mexico south to Argentina, but the range seems to be extending northward into parts of California, Texas, Arizona and New Mexico.

Bats of the genus Lasiurus generally occur in wooded areas and roost in foliage. Occasionally these bats roost in tree holes or buildings. In the U.S. L. ega is associated with introduced palms, which is thought to be a reason for its recent expansion northward.

A whitish buff, yellowish, or orange, usually with a blackish wash. Tail membrane is well furred.

Normal litter size is 2 or 3 young, although individuals have been known to have single young. Estimated gestation period is 80-90 days. Mating occurs in the late summer or fall with sperm being stored overwinter in the uterus. Ovulation and fertilization occur in the spring with births occurring from late May to early July.

These bats are generally solitary, but females of some related species are known to form small nursery colonies and form flocks of several hundred for migration. Males do not generally congregate in summer, but may congregate during winter.

L. ega eats primarily insects caught in flight but is also known to alight on vegetation to pick off insects. Feeding flights are 6-15 m. above ground.

May help to control harmful species of insects.

Several cases of rabies have been reported in Lasiurus ega in southen California. In one instance, an individual landed on a human's bare foot and punctured the toe. Before 1979, there were no known instances of this species carrying rabies.

Temperate North American bats are now threatened by a fungal disease called “white-nose syndrome.” This disease has devastated eastern North American bat populations at hibernation sites since 2007. The fungus, Geomyces destructans, grows best in cold, humid conditions that are typical of many bat hibernacula. The fungus grows on, and in some cases invades, the bodies of hibernating bats and seems to result in disturbance from hibernation, causing a debilitating loss of important metabolic resources and mass deaths. Mortality rates at some hibernation sites have been as high as 90%. While there are currently no reports of Lasiurus ega mortalities as a result of white-nose syndrome, the disease continues to expand its range in North America.