Occurrence and Integrated Control Methods of Sheep Nasal Bot Fly

Cause: Sheep nasal bot fly is a disease caused by the larvae of the sheep nasal bot fly parasitizing the nasal cavity of sheep, mainly affecting sheep. The adult sheep nasal bot fly directly deposits larvae, and the larvae become adults after passing through the pupal stage. Adult sheep nasal bot flies appear from May to September each year. After mating, the male fly dies, and the female fly rests until the larvae inside her body develop before flying and becoming active, depositing maggots in the nostrils of sheep to breed larvae. The first-stage larvae attach to the nasal mucosa of sheep and gradually migrate inward, molting into second-stage larvae in the nasal cavity and frontal sinuses, and by the spring of the following year, they develop into mature third-stage larvae. The activity of the larvae irritates the sheep, causing sneezing, and the mature larvae are expelled to the ground, where they burrow into the soil or manure and become pupae. The pupal stage lasts 1 to 2 months, after which they emerge as adults.

Symptoms: Affected sheep are restless, shake their heads, snort, lower their heads, and show nasal mucosal swelling, bleeding, and inflammation, incoordination, circling, head turning, and finally complete loss of appetite, collapsing into exhaustion and death.

Prevention and Control: 1. Use 40% dichlorvos emulsion as an aerosol to fumigate and kill the larvae, using 1 milliliter of the medication per cubic meter of space indoors. Method: Pour dichlorvos emulsion onto a heated shovel or iron tool, and once thick smoke rises, let the affected sheep inhale it for 10 to 15 minutes. 2. In summer and autumn, spray the nostrils of affected sheep with a 3% Lysol solution. 3. Administer rafoxanide orally at a single dose of 60 milligrams per kilogram of body weight. 4. Mix 0.1% into the feed at 0.3 grams per kilogram of body weight and feed it to the sheep once. 5. During the epidemic season of the sheep nasal bot fly, apply trichlorfon ointment (made with 2% refined trichlorfon mixed with waste engine oil or other oils or ointments) around the nostrils of the sheep.