Today I was walking through the pasture/desert and noticed that one of my month old calves had bald spots behind its ears and along the to of its neck. The calf is very healthy and nursing well. Is this caused by flys? I have my cows on a scheldule with the bulls to calf in the winter so I don't usually have problems with flys and calves, but I bought somes cows that were bred at a different time than mine. Any suggestions?