A REA^LSION OF THE TYROGLYPHID.^ OF THE 

 UNITED STATES. 



HABITS AND ECONOMIC IMPORTANCE. 



From an economic standpoint the Tvrog'l3^phidfe are one of the most 

 important groups of mites. But owing to their small size and pale 

 color the}' have often been overlooked and the damage accredited to 

 some larger insect which happened to be present. By their rapidity 

 in breeding the}' make up for their minute size, so that articles, such 

 as flour and sugar, are often so badly infected that the whole mass of 

 the substance appears to be in motion. It is chiefl}' thru their ravages 

 to stored foods that the}' are inimical to human effort. Dried fruits, 

 dried meats, and grain in mills are perhaps most seriously affected by 

 them. Their frequency in cheese and sugar has won them the names 

 of "cheese mites" and "sugar mites," while the disease known as 

 "grocer's itch" is due to their presence on the hands of persons 

 handling infested products. A list of materials attacked by tyro- 

 glyphids would include cheese, flour, sugar, hams, dried meats, hair 

 in furniture, mattresses, and pillows, grains in mills, cereal foods, 

 many drugs, wine, dried fruits, seeds of all kinds, bulbs, roots of 

 plants, mushrooms, feathers, hay, scale-insects, pinned insects of the 

 entomologist's collection, and even the human corpse. Some species 

 are, however, of little economic interest and occur in the nests of mice, 

 moles, and ants, in decaying bark of trees, in sap from wounds in 

 trees, and a few are attached to certain insects. The species of the 

 genus Monieziella do some good by feeding on scale-insects. The 

 "bulb mite" or "Eucharis mite," Rldzoglyplms hyaclnthl, has long 

 been a prominent enemy to hot-house cultivation. It burrows into 

 the healthy tissue of bulbs and roots, thus giving entrance to destruc- 

 tive fungi and bacteria. This is the species infesting Bermuda lily 

 bulbs; and it has lately been shown that an allied species does great 

 damage to the roots of the vine in Europe. Another species has been 

 described that caused injury to the stems of carnations. Still another 

 Rhls()glyj)hus has been found to eat through the grafting wax on 

 grafted plants, bore beneath the bark, and so prevent the union of 

 graft and stock. The mushroom mites, both in this country and in 

 Europe, are prominent obstacles to successful mushroom culture. 

 Cellars apparently clean in the beginning of the season may be so 

 badly infested by Christmas that crops are impossible. 



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