THE TICKS 



139 



14. Bifid Coxce bear two spurs and are deeply incised. When tren- 

 chant they have a knife-hke margin. 



Several stages are passed through in the development of the ticks. 

 From the eggs are hatched the six-legged (hexapod) larvce, often referred 

 to as the "seed ticks" (Plate II, Fig. 6). These are very small but 

 may be seen without the aid of magnification. The legs are relatively 

 much longer than in the adults. 



The nymph stage is reached after molting, when a fourth pair of legs 

 appears posterior to the third pair (octopod). 



The change from the nymphal to the adult stage is marked by another 

 molting, and sexual maturity is reached. 



After fertilization b}^ the male, the female slowly enlarges and be- 

 comes the ovigerous or egg-containing female. Upon repletion she drops 

 to the ground and proceeds to deposit her eggs. 



Superfamily Characteristics. Acarina (p. 94). — The Ixodoidea are 

 all blood-sucking parasites on animals. They have a movable capitulum 

 consisting of a basal portion (basis capituli), protrusi})le serrate chel- 

 icerse, a rigid serrate hypostome, and a pair of palps. The breathing 

 apertures are situated posteriorly. 



The superfamily Ixodoidea is divided into two families, — Argasidae 

 and Ixodidse. 



Family I. Argasid^ 



Ixodoidea (p. 139). — The ticks belonging with this family have little 

 sexual dimorphism as compared with the Ixodid*. The capitulum, 

 instead of being terminal, occupies in adults the ventral face of the 



■^^^ 



Fig. 79. — Argas miniatus: Fig. 3, dorsal view; 3a, ventral view; 3c, larva (after Os- 

 born, from Marx, Bui. No. 5, Bureau of Entomology, U. S. Dept. of Agr.). 



cephalothorax. The palps are leg-like, the articles very movable on 

 each other. The scutum is absent. The coxa^ are unarmed; tarsi with- 

 out ventral spurs. 



The family has two genera, — Argas and Otobius. 



1. Argas miniatus (A. americanus) (Fig. 79). The Fowl Tick. Ar- 

 gasidae (p. 139). — The lK)dy is ovoid, flattened, with edges very thin. 



