NO. 1382. 



THE ACARINA OR MITES— BANKS. 81 



attacked is the onl}' reined}'. Since man}- are carried in the hypopial 

 stage on liies, it is advisa))lo to have the windows screened in all fac- 

 tories where cereals, drugs, dried meats, and fruits are prepared. 

 When very abundant the Tyroglyphids are attacked l)y various pre- 

 daceoiis mites, chiefly Chei/letuf< and Gamasus, which greatly reduce 

 their numbers, and in some cases entireh' destroy them. 



Various species have at different times been recorded as temporarily 

 parasitic on man, causing itching and soreness of skin. Persons han- 

 dling infested products are apt to become attacked. 



The genera known to occur in the fauna of the United States may 

 be distinguished as follows: 



1. Doi^al tegument more or less granulate; claws very weak, almost invisiV)le; some 



hairs of body are plainly feathered; ventral apertures large (Injciphagus 



Dorsal tegument not granulate; claws distinct; no prominent feathered hairs; 

 ventral apertures smaller - 



2. ]\Iandibles not chelate, elongate, and toothed below; body without long hairs; 



palpi enlarged at tip, and provided with two divei-gent l)ristles; body often 



verrucose ITisiKMoma 



Mandil)les chelate, not elongate; body usually with some long hairs; palpi not 

 very distinct, not enlarged at tip, nor with the two bristles ?, 



3. Xo suture between the cephalothorax and abdomen; male lacking sucking disks 



near anal aperture; claws arising from a membraneous ])late, or else associated 



with bees -1 



A suture present; male with paranal sucking disks 5 



4. Body short; no clavate hair on base of tarsi I and 11, a coriaceous i)iece on 



anterior margin of cephalothorax, or with a dorsal shield; living on l)ees, or 



in their nests; epimera of legs I and II not connected Trirhofursus 



Body not short; with clavate hair on tarsi I and II; no coriaceous shields or 

 pieces; epimera of legs I and II are connected; claws arising from tip of a 

 membraneous extension of the tarsus; living on dried fruit C(trp()ghjj)Jnis 



5. Body elongate; hind pairs of legs arising much behind the anterior pairs; the 



Hypopus with eye-like spots Hif<tloi/((ster 



Body not elongate; hind pairs of legs much nearer to anterior pairs (i 



6. No sucker at tips of tarsi; leg I never thickened; in some males leg III is thick- 



ened ; tarsi with stout spines Rh Izoghiphus 



A sucker at tips of tarsi, although sometimes weak; leg III never thickened; no 

 spines (only bristles) on tarsi 7 



7. Leg I of male thickened; i)alpi (juite distinct and separate Alearob'ius 



Leg I of male not thickened; palpi less distinct and more appressed to rostrum. 



Tiirnriliiphtiii 



The Hypopi of the various genera, as far as known, can l)e separated 

 by the following table: 



1. A pair of clasping organs on venter near tip of body, margins not sharp-edged. 



LdhtdojiJiarKx 



No clasping organs, but an area of suckers 2 



.2. Anterior legs end in very large claws; margins of body ik )t sharp-edged . Trirliotarsus 



Claws small or of normal size 3 



3. An eye-like spot each side on anterior part of 1 x )dy Ilistlogasicr 



No such eye-like spots 4 



Proc. N. M. vol. xxviii— 04— — 6 



