Horn flies feed on lesions found on the host skin, and ingest microfilariae, as they feed on cutaneous lesions. They later develop into L3 in around 18-21 days. The definitive host is infected when the fly leaves the L3 on the host. | Horn flies feed on lesions found on the host skin, and ingest microfilariae, as they feed on cutaneous lesions. They later develop into L3 in around 18-21 days. The definitive host is infected when the fly leaves the L3 on the host. |