Last year, Weld County, Colo., had 98 human cases of the West Nile virus -- the highest number in the state. To curtail the incidence of West Nile this summer, the county Department of Public Health and Environment handed out 100 wooden boxes or bat houses in May to residents willing to host the area's bat population in their yards. Bats, which can consume up to 1,000 mosquitoes a night, are seen here as key to naturally decreasing the number of mosquitoes carrying West Nile and other mosquito borne diseases. The bat houses, which are about 2-feet high and 13-inches wide, were built and donated by the local Boy Scout Troop for people to hang from poles, barns and trees in the county. The experiment won't replace citywide spraying but will provide another line of defense aganist the virus, which is endemic to the area and state. West Nile virus "season" in Colorado begins now and lasts through the end of September. To learn more, contact the county health department at 970-304-6470, ext. 2389.