− | Horn flies feed on lesions found on the host skin, and ingest microfilariae, which later develop into L3. 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. |