IvARVA OF CEvSTRUS OVIS (GRUB) IN THE NASAL 

 SINUSES OF SHEEP. 



Season of attack by fly, bibernation, botfly of sheep, mode of attack, 

 embryo, defensive acts of sheep, habitat of larva, mature larva, its exit, 

 chrysalis in soil, its transformation. Symptoms, sneezing, snuffling, rub- 

 bing of nose, lachrymation, unsteadiness, discharge, respiratory digestive 

 and febrile disturbances, emaciation, septic action. Lesions, larva, conges- 

 tions of mucosa, brain. Treatment, warmth, errhiue, parasiticides, mechan- 

 ical extractors, trephining, injections. Prevention, newly turned furrow, 

 quicklime, tar. Other larva in nose. 



Sheep are especially subject to the attacks, in summer and 

 autumn and in warm sunny barns even in winter, of the CEstrus 

 (Cephalemia) Ovis, the larva of which hibernates in the na.sal 

 sinuses or ttirbinated bones. 



The sheep-bot-fly is only about four lines in length, of a light 

 yellowish or slightly brownish gray hue, hairy, with dull black 

 transverse lines on the upper surface of the thorax, and a lighter 

 color on the abdomen where the black lines are more broken. 

 The transparent, colorless wings extend beyond the bod}- : wing- 

 lets are long and cover the poisers : abdomen is formed of five 

 rings. 



They appear during the whole summer hiding away in walls, 

 stumps and grass, unless when pairing or pursuing the sheep to 

 deposit their young. The mode of attack is difficult to follow on 

 account of the small size, gray color and rapid flight of the fly and 

 fear and .shyness of the sheep. It cannot be doubted, however, 

 that they approach and drop on the margin of the nostril, the 

 larva previously hatched from the egg. The old authors describe 

 the deposition of the egg on the margin of the nostril and its 

 prompt hatching by the animal heat, but the observations of 

 Brown, Kelly, Cockrill, Riley aud Ormerod abundantly prove 

 that the fly is viviparous. Cockrill obtained no less than 300 live 

 hatched larvae from one fly caught while pursuing a sheep. 



The sheep seek to avoid the fly by resorting to dry dusty roads 

 where they lie with the nose clo.se to the ground, or they .stand 

 with the nose close to the soil and between their fore legs. At 

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