﻿5^HE CATTLE GETJBS OR OX WAEBLES 



41 



3. — It is not necessary to apply friction to the eggs to cause 

 them to hatch, as the larvae have been observecl in many instances 

 by the writers and others to cruwl from the shells when their 

 development was completed, provided the proper temperature was 

 maintained. 



4. — ]\Iuch skin irritation in areas where eggs have been attached 

 to the hairs is in evidence about four days after the eggs have 

 been deposited. It has been observed repeatedly that violent stamp- 

 ing, kicking, and licking of the affected parts by the host occur 

 soon after the hatching of the eggs begins, and a few days later 

 soreness and the formation of scabs due to the exudation and 

 hardening of serum are apparent. "NMien these scabs are removed, 

 a cluster of hatched eggs is usually 

 found attached to the hair in their 

 midst. (Fig. 21.) 



5. — The actual penetration of a 

 number of larvse soon after hatch- 

 ing has been observed by the 

 writers and their associates. This 

 process will be described later, 



6. — Stub (95) has been able to 

 trace the route pursued by young 

 larvae from the inside of the right 

 tibia over the shoulder and around 

 the muscles of the neck to the 

 connective tissue of the esoph- 

 agus. 



Taking the evidence set forth 

 herein and considering the obser- 

 vations of other investigators 

 whose work entirely corroborates 

 it, there seems now to be no doubt 

 that the normal method of ingress for the larvae of both H. lineatum 

 and H. hovis is directly through the skin at the point where the eggs 

 are attached, and proves that there is comparatively little likelihood 

 of infestation occurring by means of larvae taken in by the mouth. 

 It is desirable to stress at this point the demonstration given, by the 

 slaughtering of some of the animals as above outlined, that the larvae 

 entering cattle through the skin on the lower legs may be found in 

 the gullet in considerable numbers during the succeeding months. 

 This proA'es the fallacy of the suggestion frequently made by investi- 

 gators that those larvae which are found in the gullet were probably 

 taken in by the mouth and that they may perish and never reach the 

 back. It should be noted that the writers have shown herein that 

 larvae of 11. lineatum removed in the second instar from the gullets 

 of cattle and introduced under the skin of uninfested bovines will not 

 only appear under the skin on the backs of the new hosts in the 

 proper season, but may and probably usually do pass again into the 

 body cavity and even return to the gullet before going to the back. 



DEVELOPMENT AND HABITS 



NUMBER OF EGGS ON HAIK 



The eggs of //. lineatum are usually liii«l in a scries of froui 5 (o li2 

 and occasionally as many as 20 iniiy be attached (o a single hiiic. The 



Fig. 21. — Scab removed from a lesion 

 on a cow, caused by penetration of 

 newly-hatched larvaa of Hypodcrma 

 lineatum. Note the three hatched eggs 

 on the hair 



