External Parasites 229 



pest. The following notes are taken from a paper by 

 Laurie.^ 



These parasites belong to the group of mites Acari. In 

 the adult stage they have four pairs of legs but in the larval 

 stages only three pairs (Figs. 49 and 50). 



These ticks are nocturnal in habit. During the day they 

 secrete themselves in cracks and crevices and are rarely 

 seen. At night they come out on to the roosts and fasten 



Fig. 50. — The poultry tick. Larva, showing the three pairs of legs. (After 



Laurie.) 



themselves upon the birds. After gorging themselves with 

 blood they return to the cracks to digest their meal. An 

 adult tick feeds only about once a month, as it requires that 

 time to digest fully one meal. During the growing periods 

 they undergo a molt after digesting each meal. These 

 ticks breed very prolifically, so that a poultry house once 

 infested soon becomes overrun by them. 



1 Laurie, D. F. The Poultry Tick. Dept. of Agrie. of South 

 Australia, Bui. No. 74, pp. 1-32, 1912. 



