THE TICKS 



139 



14. Bifid CoxcB bear two spui's 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) larvcB, 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 by the male, the female slowly enlarges and be- 

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

 to the groimd 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), protrusible serrate chel- 

 icerse, a rigid serrate hj'^postome, and a pair of palps. The breathing 

 apertures are situated posteriorly. 



The superfamily Ixodoidea is divided into two families, — Argasidse 

 and Ixodidse. 



Family I. Argasid^ 



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

 sexual dimorphism as compared with the Ixodidse. 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; 3e, larva (after Os- 

 bom, from Marx, Bui. No. 5, Bureau of Entomology, XJ. S. Dept. of Agr.). 



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

 each other. The scutum is absent. The coxae are imarmed; tarsi with- 

 out ventral spurs. 



The family has two genera, — Argas and Otobius. 



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

 gasidse (p. 139). — The body is ovoid, flattened, with edges very thin. 



