334 A carology 



1937, on the other hand, found that Rhizoglyphus echinopus (Fu- 

 mouze and Robin) produced most hypopi under wet, sticky conditions. 

 This has also been observed in species of Histiostoma and Calogly- 

 phiis. 



The heteromorphic male is to be found in various genera of the 

 Acaridae, and that of Rhizoglyphus echinopus is shown in Figure 261. 

 With some species it is rarely found, but with R. echinopus as high as 

 20 per cent of the males may be heteromorphic. They may be easily 

 distinguished by the enlarged third pair of legs. These males breed 

 with the females and produce both types of males as well as females. 

 The normal male, mated with a female, will also produce the same 

 type of offspring. 



Rhizoglyphus echinopus (Fumouze and Robin), the well-known 

 bulb mite, is cosmopolitan in distribution and may be found in bulbs 

 of amaryllis, crocus, Easter lily, gladiola, hyacinth, narcissus, and tu- 

 lip. It can probably feed on most tubers, especially those which have 

 loose scales permitting the entry of the mite. Shipments are usually 

 infested with this mite, which may destroy as high as 15 to 20 per cent 

 of the bulbs. However, the rotted area is not always due to the mite 

 but can be caused by other factors. In the field the mite apparently 

 does little damage to healthy plants, affecting only rotted bulbs, but 

 if the mites become established in stored bulbs they appear to hasten 

 decay. Although it usually feeds on rotted or decayed tissue the mite 

 can infest healthy tissue if in contact with it. This indicates the neces- 

 sity of eliminating rotten, infested bulbs to prevent the spread of the 

 mite in storehouses. The mites probably carry fungus and bacterial 

 diseases with them externally. 



Tyrophagus lintneri (Osborne)^ is a widely distributed pest, seri- 

 ous in stored foods, and at one time on cultivated mushrooms. The 

 mites eat the spawn and make holes in the stems and caps of the 

 mushrooms and can seriously hinder mushroom culture if not con- 

 trolled (Davis 1944). It is to be found in greasy soda fountains and 

 in cupboards wherever food is available. 



Thyreophagus entomophagus Laboulbene has been found associated 

 with dried insects in collections and with scale insects in the field. Al- 

 though occasionally reported as being predaceous on the scale insects 

 they actually live on the cast skins and dead scales, which must be 

 slightly moist. In brief, it can be said that this mite lives on dried ani- 



1 Caloglyphus sp. has displaced Tyrophagus lintneri in mushroom houses in Mary- 

 land and Pennsylvania withn the last few years. 



