Spiders and Their Near Relatives 



In the Hydrachnidae (Hy-drach'ni-dae) the body is short, usu- 

 ally high, and sometimes nearly spherical. There is no division 

 between the cephalothorax and abdomen. They have one or two 

 pairs of eyes, which in some cases are situated near the median line. 



In most species the adult mite lives free in the water, but 

 some are parasitic in the gills of mollusks. Nearly all of the 

 species live in fresh water; but some are found in brackish water, 

 and a few live in the littoral zone of the sea. The free species 

 feed on small Crustacea, infusoria, and minute insect larvae. 



The larval mites are often found attached to aquatic insects; 

 they appear like club-shaped eggs attached by the small end. 



Superfamily IXODOIDEA 

 (Ix-o-doi'de-a) 



The Ticks 



Of all mites, the ticks are the 

 ones that most often attract the 

 attention of those who are not 

 making a study of this order. This 

 is due to the fact that they attach 

 themselves to man and to domestic 

 animals and are exceedingly an- 

 noying pests. This is especially 

 true in the warmer portions of the 

 country. Among the ticks are also 

 the most important members of 

 the order from an economic stand- 

 point as certain species transmit 

 serious diseases. 



Ticks are parasitic on mam- 

 mals, birds, and reptiles. In most 

 cases they do not seriously injure 

 their host, but in others they cause 

 serious inflammation and swelling 

 of the infested part. Among those 

 that transmit diseases the Southern 

 cattle tick is the most important one that occurs in this country. 



It is the Southern cattle-tick, Boophilus annulatus (Bo- 

 oph'i-lus an-nu-la'tus) (Fig. 64) that transmits the tick-fever, 



8q 



Fig. 64. THE CATTLE TICK 

 a, female b, male 



