50 REPORT OX INJURIOUS INSECTS FOR 1907. 



sporocyst, within whose body are produced a second generation known 

 as rediae, these force their way out of the sporocyst and now wander 

 about the body of the snail. 



The next change is that in the bodies of these rediae a series of tailed 

 forms knoxvn as cercariae are formed, they escape, and then work their 

 way out of the snail, and as this snail is amphibious, and is often found 

 outside the \vater, the cercariae may be set free either in the water or 

 on the grass. On the grass they lose their tails, become encysted, and 

 are swallowed by the sheep with the grass. In the stomach of the 

 sheep they escape from their cysts and make their way into the bile 

 ducts, and in about six weeks time become fully developed liver-flukes. 



PREVENTION AND TREATMENT. 



Wherever rot is found amongst a flock of sheep it is better to 

 send them to the butcher at once. If this is not practicable, they 

 should be moved on to well-drained, dry ground, and given a daily 

 allowance of salt, and plenty of dry nutritious food. It is not advisable 

 to leave sheep for any lengthened period on the same pasture. 



Livers of affected sheep should not be fed to dogs raw, but first 

 well boiled. 



Pastures known to have had infected animals on should be treated 

 with lime, all ditches and ponds should be cleaned out, and all coarse 

 grass, reeds, etc., should be cleared out and treated with unslaked or 

 gas lime. 



THE 'GID' PARASITE. 



Taenia caenunts, Kuch. 



One of the most serious parasites affecting sheep is the larval stage 

 of a tapeworm parasitic in its adult condition in the intestine of dogs. 

 The disease it gives rise to is commonly termed gid, staggers, sturdy, 

 or turnsick. 



The disease has been known to flockmasters and others for nearly 

 three hundred years, and it is estimated that it causes an annual loss 

 of ten per cent in this country. In other countries, however, it has 

 risen to thirty and forty per cent. 



LIFE- HISTORY. 



A dog infected with Taenia caenurus the species of tapeworm, 

 scatters the eggs and gravid segments on the ground. In moist places 

 these may live for some weeks, but if exposed to hot, dry \veather 

 they soon die. 



Both sheep and cattle swallow some of these eggs when either 

 drinking or grazing. Once they reach the stomach of the host, the 

 digestive juices dissolve the shells of the eggs and set free the embryo, 



