39 



when it is cool. Lounsbury found that entire life cycle from egg to 

 egg required 10 months in one case studied. Great longevity; we 

 have kept specimens unfed and in a dry tin box alive for nearly two 

 years. Instances on record of survival for three years. (See, 

 Nuttall, '08). 



Economic importance — Bite often causes serious injury to man. 

 Aside from importance in some regions as transmitters of poultry 

 disease, they are directly responsible for the death of many fowls 

 and for much loss due to depleted condition. 



Means of control — Cleanliness of poultry houses and yards, white- 

 washing (filling all cracks), removal of rubbish under which ticks 

 can hide. Use of dips to kill the ticks on fowls. 



B — Ixodidae — Dorsal shield or scutum present; sexes very distinct 

 in appearance; palpi relatively short and rigid. Nymphs and adults 

 remain attached to host for days or months, increasing enormously 

 in size when gorged. Not so long-lived as typical Argasidae. 



Boophilus annulatus — "Margaropus annulatus" , the Southern 

 cattle tick. Causes enormous direct loss, but it is as a carrier of 

 Texas fever of cattle that it becomes one of the most important 

 pests of the South. Conservative estimates place losses to the South 

 due to it as $40,000,000 annually. 



Life history — Mate on host, female drops to the ground and 

 deposits many eggs. After twenty to twenty-five days in summer, 

 or months in the fall, "seed ticks" or larvae emerge, crawl to top of 

 grasses and bushes, where they await their host. After six or seven 

 days on the host molt and form nymphs with eight legs. During 

 nymphal stage sexual organs develop. In from five to eleven days 

 the nymphs molt and appear as adults. In summer, female feeds 

 six to twenty days after copulation before dropping from the host to 

 lay her eggs. 



Relation to Texas fever — Since the discovery of the causative 

 organism of Texas fever by Smith in 1889, it has been clearly demon- 

 strated that the disease is not transmitted by saliva, urine, or manure 

 of diseased animals but solely by the cattle ticks, hatching from eggs 

 laid by individuals which had fed on diseased cattle or on apparently 

 healthy Southern cattle which carried the parasite in their blood. 

 Not only the clearest of circumstantial evidence, but proved experi- 

 mentally very many times. 



