- Larvae of these flies spend most of their time in the nasal passage of sheep & Goat. So called nasal bots
- Adult flies are having short life span (1 week) whereas larvae having 1 year or more of life span.
Morphology
- Adult flies are 1cm in size and of grey color.
- Small dark spots are present on the abdomen with a covering of short brown hair.
- Size of Larvae is 3cm and color is yellowish white. Larva is tapering anteriorly with prominent step posteriorly.
- Body is segmented having dark transverse bands dorsally (each segment).
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| Nasal Bot fly injecting larvae |
- Adult female is viviparous and produce larvae.
- Sheep become infected by squirting of jet of liquid containing larvae.
- During the flight, fly deliver 25 larvae.
- Newly emerged larva is 1mm in length.
- Larva migrates from nasal passage to frontal sinuses.
- Larva feed on mucous secreted by movement of larva.
- In the nasal passage, larva mould to L2.
- In the frontal sinuses, larva completes their development and then migrates to nostrils where they are active throughout the year.
- Become dormant in winter season if temperature is below 18.
- From the nostrils, L3 larvae fall on the ground and from larva, pupa develops.
- From the pupa, adult emerges. Adult having very short life span
- Survive for only 1 week and during this period, produce about 500 larvae.
Pathogenic effects
- Itching and Irritation
- Rubbing the nostrils against hard objects
- Nasal discharge which later on becomes mucopurulent
- In coordination, convulsions
- Also called false gid (signs resembling coenurus cerebralis)
- Cause swelling of eyes in human called as keratoconjunctivitis and inflammation of lips called stomatitis
- Loss of weight
Treatment
- Refoxanide, Ranide…. 1ml/25kg BW subcutaneously
- Nitroxynil, Trodex….1ml/20kg BW subcutaneously
- Ivermectin………….1ml/50kg BW subcutaneously
Control
Regular use of insecticidal drugs should be followed.
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