116 



EEPOKT 108, U. S. DEPAETMEXT OF AGEICULTURE. 



Tyroglyphus, the typical genus, is known in this country by 9 or 10 species, 3 of 

 which are very common. One, a species in grain and stored foods, is T. americanus 

 Banks. Another common species is the mushroom mite, T. Untneri Osborn (fig. 236), 

 which is very close to the European T. longior Gervais, but having the bristles smooth. 

 This species at times is very destructive to cultivated mushrooms, and once in a bed 

 it is very difficult to eradicate it. Busck has given an account of experiments against 

 it Avhich serve to show the difficulty of dealing with the pest. Severely infested beds 

 should be destroyed, and perhaps if the earth was steam heated (as is done for root- 

 worms) the eggs would be killed. T. longior has the long hairs of the body distinctly 

 plumose; it has been found in great abundance in barns and mills in Canada and the 

 Northern States. Two species, T. breviceps Banks and T. annipes Banks, have been 



taken from the dead larv^a? of insects, and several spe- 

 cies have been found in ant nests. Dr. Felt has de- 

 scribed a species, T. heteromorphus Felt, which caused 

 injiuies to the stems of carnations grown in gi-een- 

 houses, and the same species occurs in other decay- 

 ing vegetable matter. The third pair of legs are en- 

 larged in the male. 



The genus Aleurohius has been used for a species of 

 Tyroglyphus, T.farinse De Geer (fig. 235), the male of 

 which has enlarged front legs. This species appears to 

 be well-nigh cosmopolitan and is most commonly 

 found in flour, gi'ain, and stored foods. The great en- 

 largement of the anterior legs of the male is a unique 

 character in the famih\ The body has a few rather 

 short hairs. Cleanliness, window screens, and fre- 

 quent handling of the grain will be the best prevent- 

 ives for the protection of mills against this pest. 

 Fumigation with hydrocj^anic-acid gas is the best 

 remedy, but it may be necessary to repeat the treat- 

 FiG. 2?,^.— Monieziella sp.: Female. ment several times, as it is a difficult matter to de- 

 (Author's iUustration.) gtroy these mites. 



The genus Monieziella (figs. 239-241) contains species that are predaceous on scale 

 insects. Three species are known from this country, two on Aspidiotus and one on 

 Mytilaspis scales. It is not certain whether they feed on the living scale insects or 

 only upon the dead ones, but it is probable that they do both. They are fairly com- 

 mon and undoubtedly do much good in checking the increase of these pests. 



To the genus Rhizoglyphus belong a niunber of species, found on the ground, in 

 decaying matter, on roots of plants, and in bulbs. The body is slightly more p^Tiform 

 than in most tjToglypMds, and the species are of rather large size. We have se\-eral 

 species in the United States. One of them is the B. hyacinthi Boisduval (fig. 238) 

 {R. echinopus Fumouze and Robin). Tliis is the "bulb mite'' or "Eucharis mite" of 

 the horticulturists and is responsible for an enormous amount of damage. It burrows 

 into healthy tissue, thereby giving entrance to destructive fungi and bacteria. It is 

 especially common in hothouses, where its ravages on orchids ha^-e long been known. 

 No one appears to have found a successful treatment. The best way is to burn the 

 affected bulbs as soon as discovered. Some growers, however, secure good results by 

 the following treatment: The soil of the pots of infested ])lants is allowed to become 

 dry; then the bulbs are taken out and washed in a solution of tobacco water and soft 

 soap, with a small amount of washing soda. Then they are sprinkled with freshly 

 slaked lime and left for two days. Then they are washed with the same solution as 

 before, to which a little petroleum has hoon added. They are then repotted and 

 often do well. Mr. Woods has shown that this mite, when infesting Bermuda lilies, 

 can not be destroyed, but much good is accomjilished by the use of commercial fer- 

 tilizers and rotation of crops. R. rhizophagus Banks (fig. 237) is a similar form. 



