calves losing hair?

I have 2 young calves, about 1 month and 2 months, that are losing their hair under their tail on their [[ i guess it would be flank ?? ]] and behind their ears. One of them had mites that have now gone away, but the younger one is losing that hair above his hocks and below his tail head to where hes practically bald. I know its too early to worm them so what else can i do??
Thanks in advance

THe only thing that come to my mind at the moment is  Biting Flys.  They are eating our calves alive this year.  However, if you have a bunch of calves and only 2 have this problem, it is probably something different.  Do they have Scours?  Are they walking though something that may be rubbing hair off?  Are there any wounds or blood where the hair is missing?  Can you pull hair out around the effected area?  Good luck!  Hope you can figure it out and fix it.

Good Luck
Fluffer

As spring is here, the number of flies and external paraites have increased.  It could be Biting flies, but if that were the case, then I would expect for you to see it on the other animals.  I know that with young calves, the mother cows will lick the hind end of the calf while it is nursing to stimulate it to excrete waste.  This licking compiled with warmer weather conditions can cause the hair to fall out.  If the affected area is in other regions such as the "twist" (area between back legs underneath the tail), and around the ears, there might be a more serious problem than an overzealous mother.  I would suspect that it could possibly be a fungus or other external parasite.  Although fungus is very contagious, some fungal infections will not appear on older or otherwise more immune animals, although it can and more than likely is still present.  I would recommend treating the calves with iodine on the affected areas, and using some sort of external parasite/fungal medication on the older animals.
JR Cattle Co.