108 VETERINARY PARASITOLOGY 
Instead of being oval, as in the case of the ova of 
Céstrus equi, the ova of Gstrus ovis are kidney-shaped. 
The larve have the body white, x inch in length, and 
divided by dark transverse streaks. The dorsal surface 
is rounded and convex from side to side, while the 
ventral surface is flat, and on this surface each segment 
after the third carries red pointed spines, laterally 
situated, leaving a plain middle portion. 
The larva spends about ten months within the nasal 
cavities, after which it escapes and becomes a chrysalis. 
This stage lasts six months, and the adult stage is then 
attained. 
Symptoms.—When a number are present in the nose, 
frontal sinuses, or horn-cores, there may be unilateral 
nasal discharge, purulent or blood-stained in many 
cases, with repeated rubbing of the nose against other 
objects. The head is carried a little to one side and 
frequently shaken. Occasionally the symptoms resemble 
those of gid. Epileptiform convulsions may occur, and 
death may follow. Ova may also be present in the 
larynx, trachea, or may reach the brain by passing 
through the ethmoid bone. 
TREATMENT. — Fumigation. Trephining the horn- 
cores in some cases. 
PREVENTION.—Where the fly is common it is best to 
use special feeding-boxes, with apertures of sufficient 
size to admit only the nose. Tar mixed with fish-oil is 
smeared around the apertures, so that the nose is 
constantly dressed with the mixture. This usually 
suffices to keep the fly at a distance. 
BRONCHIAL STRONGYLES. 
These parasites inhabit the trachea and bronchi of 
various animals. They have the caudal pouch sup- 
ported by chitinous rings, but the mouth is non- 
chitinous. 
