648 Journal of the Department of Agriculture, 



Where Infection Lies. 



As in appearance, so in life-history, the spinose ear-tick is' 

 different from all other cattle ticks. It is a pest of the stable and the 

 kraal much more than the veld. Where the tick has lately made its 

 appearance the milk cows in the kraal, particularly if they sleep 

 there, may be heavily infested while the dry cattle in the veld are 

 clean, a fact no doubt due to a peculiarity in the li*fe-cycle of the tick 

 to be later noted. The females are said to lay their eggs in cracks 

 and crevices of fencing- posts, in stone walls, and under stones in the 

 veld. Personally, however, the writer was not successful in finding 

 adult ticks in any of these places. The favourite place would appear 

 to be the loose, dry manure which fills the spaces between the stones 

 at the bottom df the kraal wall and some distance in — six to nine 

 inches. Here numerous adults, male and female, were found, and 

 large numbers of newly hatched larvae. These are remarkably act.'ve 

 six-legged little creatures, and resemble the colour of their surround- 

 ings so much that they are hard to find. They are present in greatest 

 numbers close to the base of the wall, and rapidly diminish in numbers 

 with each yard of distance from the wall. The farthest distance 

 from home where odd larvae were seen was six yards. Like " seed " 

 ticks in the veld, the ear-tick larvae become greatly agitated and 

 extraordinarily active on the ap])i-onch of a host and move relatively 

 at a great rate. Any one standing for a minute or less within the 

 precincts of a colony will notice on close observation ticks making 

 towards him ifrom all directions. Cows and calves lying near the 

 walls of an infected kraal are practically certain to have a number of 

 larvae in their ears jiext day, although they will not be seen for 

 several d.ays, when the ticks are partially engorged. 



Stages of Development. 



In the case of a sheep that was infected for experimental purposes 

 larvae took from six to ten days to get through the moult. The fed 

 larva before moulting is milk-white in colour; a few are bright pink. 

 The legs cannot be distinguished unless under low power of the 

 microscope, neither is any movement to be seen; the fed larva has 

 about eight times the bulk of the unfed form. The emerging nymph 

 is somewhat leggy, wrinkled, and thick skinned, the latter allowing 

 for abundant expansion and the former providing <or the easy trans- 

 port of a very much bulkier body. This is now the unfed form of 

 the familiar spinose ear-tick, although it would never appear so, so 

 great is the difference in size between the newly moulted and the fully 

 fed 'forms. Without leaving the ears the nymph settle down to feed 

 again, and in the case under observation all the ticks had left the 

 ears in thirty-six days. This feeding period varies greatly, however; 

 according to Mr. Bedford, of the Division of Veterinary Research, it 

 varies from one week to three months. The nymphs moult in about 

 three weeks — this time also varies — and in another four weeks 

 females may be seen laying eggs. When the nymphs leave the ears 

 they do not return to a host again, but, crawling to some sheltered 

 spot, they moult and pair without further nourishment. The adult 

 ticks are the same size as the fed nymphs, and differ in having a 

 minutely pitted skin and no spines. They also show genital orifices, 

 which i^TP nl^sent ii) fhe nymphal forms, . 



