150 Veterinary Medicine. 



Tetranychus Molestissimus. Bicho Colorado. A. large 

 mite allied to the trombidium and like it living on green leaves, 

 preys also on cattle in the Argentine Republic and Uruguay. It 

 takes its name from the four large, strong booklets on the tarsi. 

 It demands similar precautions with the trombidium. 



SARCOPTID^. 



General characters : Body white, soft, eyeless, two pairs of legs near ros- 

 trum, and two from postero-lateral part of the body, tarsi one-hooked ; larva 

 hexapod. Divisions of Sarcoptidse. Genera of Sarcoptidae Plumicola. 



This family of mites comprises those producing ordinary forms 

 of scabies, scab, or mange, and possess the following common char- 

 acters : Body white or reddish, o. i to i mm. in diameter, soft in 

 the normal larva, nympha and adult, (.some hypopial nymphse in 

 certain genera coriaceous) ; without eyes ; respiratory apparatus 

 invisible or incomplete ; rostrum formed by the union of jaws, 

 lip and tonguelet, and concave internally ; ma.jdibles short claw- 

 like ; palpi with three segments ; legs with five segments, two 

 pairs being attached near the rostrum and two pairs to the back 

 part of the body ; tarsi with one (rarely more) terminal hook and 

 caruncle or bell-shaped sucker. Oviparous. Larvae hexapods. 

 Megnin divides the sarcoptidse into the following five groups : 



1. Sarcoptidae Detricola are never parasitic but live on de- 

 composing animal and vegetable matters. 



2. Sarcoptidae Plumicola which live in the feathers of birds 

 on cutaneous secretions and do not harm the skin. 



3. Sarcoptidae Cysticola which live in the connective tissue 

 or air cavities of birds and only injure mechanically. 



4. Sarcoptidae Gliricola which live among the hair or fur of 

 rodents and do not injure the skin. 



5. Sarcoptidae Psorica which bite or burrow in the skin, and 

 even at times poison it, causing congestion, itching, abrasion, 

 depilation, and resulting disorder. 



The first group does not interest us, seeing that its members 

 only get on animals by accident, and temporarily and are harm- 

 less. 



