Face flies feed on secretions from their host, such as tears saliva, nasal mucous, or blood and serum from wounds. The life cycle of the face fly is about three weeks during the summer. The pupae are white are white, which contrasts other manure-inhabiting flies that have white larvae and brown pupae. Face flies are attracted to both adult cattle and calves, so both need to be treated. Horn Flies are about half the size of stable or house flies and have piercing and sucking mouth parts.
Female horn flies deposit eggs in fresh manure, where the larvae complete development.
They then move below the manure into the soil to pupate. Their lifecycle from egg to adult can be completed in 10 to 20 days. Horn flies are found on the backs and bellies of cattle where they feed on blood, and are mainly attracted to adults. It is estimated that each fly bites 20 to 30 times per day. Multiply that by the hundreds of flies that can be found on cattle, and the huge economic losses are understandable.