TICKS OF THE BELGIAN CONGO. 347 



Unfed larvae kept in tubes in the laboratory were lively after 369 days ; nymphs 

 -scarcely live more thaij 90 days, whereas adults live much longer. A couple of females, 

 after fasting 817 days, have been fed on a sheep and been put with males which had 

 fasted 210 days ; these females produced offspring in due course. The life-cycle 

 may be completed in 116 days. 



Hosts : cattle, sheep, horses, and many other animals, both wild and domesticated. 



Relation to Disease : H. aegi/ptium has not as yet been shown to convey any disease, 

 but we s aspect that it may carry Nuttallia equi, one of the two species of Piroplasma- 

 like parasites causing " biliary fever " in horses. The suspicion is based upon the 

 agreement between the geographical distribution of the blood parasites and the tick 

 in Africa, Southern Europe and Asia. The subject is at present being investigated 

 .experimentally in Cambridge, 



The effects of the bite may be troublesome. 



Amblyomma hebraeum. The only two species of African Amhlyomma whose life- 

 histories are known are A. hebraeum and A. variegatum. The latter appears to have 

 no pathogenic significance ; it has the same habits as A. hebraeum in requiring three 

 hosts upon which to feed in the larval, nymphal and adult stages. A female 

 A. hebraeum may lay up to 18,500 eggs in 8-11 days at 30° C, the process lasting longer 

 at lower temperatures. The eggs, laid upon the ground, hatch after about 50 days 

 and in about a week the larvae are ready to feed. They attack a variety of hosts, and, 

 dropping off gorged after five or more days, undergo metamorphosis in about 12 days, 

 when the nvmphs cast off the larval skin. The nymphs are ready to feed in about a 

 week, remain usually six days upon the host, and, when replete, drop to the ground. 

 The adults, male and female, emerge after about 18 days. The males are 

 more numerous than the females and the latter do not readily attach themselves to 

 the host unless they find males already attached. Copulation takes place upon the 

 host, the female swelling up to a great size (about 3 cm. in length) and abandoning 

 the host after about 6-12 days. The female after hiding herself in the ground, begins 

 to oviposit in 8-74 days, according to the temperature. The males may remain 

 anchored upon the host for 41-355 days awaiting a fresh female. Under optimum 

 conditions in the laboratory the life-cycle from egg to egg has been completed in 

 171 days. 



Relation to Disease : So far as known, A. hebraeum is the only species of Amblyomma 

 which conveys disease. It is dreaded in South Africa because it carries " Heart- 

 water," a frequently fatal disease in sheep, goats and cattle, due to an undetermined, 

 probably ultramicroscopic, organism. The disease and the tick are confined to Africa. 

 When the tick feeds as a larva or nymph upon an infected animal it transmits the 

 disease after attaining the nymphal or adult stage respectively (Lounsbury). 



Apart from this the tick causes a considerable amount of trouble by its bites, which 

 may cause swelling and lead to suppuration. 



Eradication : This tick has been successfully eradicated in parts of South Africa 

 by the frequent application of the dipping process. The tick resists starvation for 

 long periods, thus laboratory experiments have shown that unfed larvae may survive 

 for 346 days, nymphs for 250 days, adults for upwards of two years. The adults may 

 remain attached to a dead host until they die. 

 (C221) c 2 



