I have a 4 day old calf that has gotten maggots on his rear an underneath. I just discovered the problem. In not really sure what to do other than clean him up. I sprayed gin down good with a premertherin mix and wiped hin down the best I could but he was putting up a pretty good fight. He is coated heavily. Will that kill them? Around his anus he was bloody looking and I could tell flies had worked on him. Thi is a first for me as the flies have just now gotten bad around here. Any advice?