I feel like I am constantly battling lice. Is that normal?! Whenever I notice them I dust the birds with a wheelbarrow mix of DE, Sevin and Poultry and Garden Dust. Clean coops and repeat a week later. Should I just go back to Sevin straight up? Dust 3 weeks in a row?? Such a frustrating and messy task! I have about 20 adult birds and 19 chicks ranging from 4 days old to 10 weeks...What do I do about the chicks' lice???