86 



REPORT 108^ U. S. DEPARTMENT OF AGRICULTURE. 



Under the name Antennophori (fig. 170) are placed a number of species and genera 

 usually associated with ants. This group is recognizal^le on account of the generally 

 circular shape and short legs, the first pair of which lacks the claws and caroncle, but 

 is provided with long hah's at the tip. The dorsum is covered by an entire sliield, and 

 the male genital aperture is in the sternal plate. The habits of these mites are in- 

 tensely interesting. The adult mites occur on ants or myriapods, one species, how- 

 ever, on an earth-boring beetle, Semites. Those on ants (fig. 171) axe usually upon the 

 head or venter. The ants are accustomed to touch one another by the antennae in 

 asking for food; the ant having food thereupon regurgitates a drop, which is taken by 

 the other ant. The mites come in here and secure a bit; by touching with their 

 front legs the ant they are on, or another ant that comes near, the mites imitate this 

 request for food, the ants often responding. Janet has claimed that the mites arrange 



,ali 



Tig. lG8.—H'jpoaspis mexkanus, mandible, and Fig. l(J9.—Hypoaspis macropilis and caroncle 



enlarged hair. (Author' sillustration.) tarsus IV. (Author's illustration.) 



themselves systematically on the ants so that they balance and do not disturb the 

 equilibrium of the ant. Thus when there is but one mite present it clings to the me- 

 dian surface of the head; when two are present, one is situated each side of the head; 

 if three, one each side and one in the middle; if four mites, then two each side, usually 

 one pair on venter; if six are present, then placed as with four, and a median one on 

 head and venter. One can hardly believe that any such definite arrangement is regu- 

 larly maintained. The species occumng on myriapods are supposed to feed on tlie 

 secretion of the repugnatorial glands. They do not arrange themselves symmetrically 

 on the host, and move about very rapidly if disturbed. They can travel as easily side- 

 wa3''S or backwards as forwards, and to this fact, Tragardh tliinks, is due their circular 

 shape. Only the adults occur on insects, the immature stages, at least vntli the myria- 

 podophilous species, according to Trag§.rdh, occurring in fallen decavdng leaves. The 



