THE ACAEIXA OR MITES. 



107 



In various parts of Europe similar species of mites have caused similar dermatitis. 

 Laborers carr\ing sacks of grain or working in the fields were attacked by mites, caus- 

 ing an eruption somewhat like nettle rash; this was called "grain fever" by the peas- 

 antry. In Hungary Geber records a mite, which he called Chrithoptes monunguicu- 

 losus, attacking men handling barley and causing an irritating inflammation of the skin 

 so severe as to force the men to leave their work. Kramer also ol^served the mite 

 under the same conditions. In France Lagreze and Robin have recorded similar 



Fig. 220.~Tarsoncmus latus: 

 Male. (Author's illustra- 

 lic.-i.) 



Fig. 



221. — Tarsonemus, side view. 

 (Original.) 



cases, attributing the disease to Pediculoidcs tritici Lagreze. Various other cases are 

 known from Roumania and Russia, so that this mite probably causes trouble in all 

 grain-growing regions, and can only be eliminated by destroying the insects that 

 commonly infest grain. In our country these cases have been confined to the Eastern 

 States. If the wheat is thrashed immediately after harvest and directly from the 

 field, the injurious insects will be largely destroyed, and there will be no damage from 

 Pediculoidcs; however, it is not advisable to use fresh straw for mattresses. 



Fig. 222.— Podapolipus, male venter; female, 

 replete, side view. (Original.) 



Fig. 223.— PigmeophoTus america- 

 nus, from above, and tarsus en 

 larged. (Author's illustration.) 



Several other species have been assigned to this genus which feed on grain and 

 grasses. One would suspect that they would fall in a separate genus, for which the 

 name Siteroptcs Amerling is available. One is P. tritici Lagreze, found in wheat heads; 

 another is S. camca Banks (fig. 217), abundant in deformed heads of some wild grasses 

 in Colorado and New Mexico, where it produces a "silver top." 



Pigmeophorus (figs. 223, 224) is closely allied to Pediculoidcs. It has a migratorial 

 form, which in one case was found on a mole and in another on a fly. We have ob- 



