518 



Mr. S. Hirst on the Mite associated with 



Note. — Apparently only adult bees are infested by this 

 mite, wliicli lives in the tracheal tubes of the head and thorax. 

 It is not known liow infection takes place — possibly by bees 

 visiting the same flower or drinking-plaee. Many species of 

 Tyroglypliidae have a migratory or travelling stage (hypopiis), 

 but this stage is not known to occur- in the Tarsonemidse. 



In his "Acarina or Mites" (Report No. 108, U.S. Dept, 

 Agricult. 1915, p. 109) Mr. Nathan Banks asserts that " The 

 curious [Tarsonemid] genus Scutacarus has a migratorial 

 nymplial stage much like the hypopus of the Tyroglypliidae. 



Fin'. 7. 



Acarapis woodi. 



a, last leg of female ; b, ovum, greatly enlarged ; c, first leg of larva ; 

 d, second leg of larva. 



Tliis stage has been found on bees and ants," This is a 

 mistake, however, for it has been pointed out by Michael 

 ('British 'Jyroglyphidse,' vol. i. p. 126), and also by Eiizio 

 Reuter in his very excttllent paper " Zur Morpholoo-ie und 

 Oiitogenie der Acariden " (Acta Soc. Fennicse, xxxvi.''l909), 

 that the nyniphal stage is suppressed in .Disparipes [ = Sculu- 



carus] 



The hypopial stage is always a nymph, and there is no free 

 nymphal stage either in Acarapis or Tarsoiiemus ; so that it 

 is probable that the disease spreads through the adult mite. 



