518 On Acarapis woodi, Rennie. 
Note.—Apparently only adult bees are infested by this 
mite, which lives in the tracheal tubes of the head and thorax. 
It is not known how infection takes place—possibly by bees 
visiting the same flower or drinking-place. Many species of 
Tyroglyphide have a migratory or travelling stage (hypopus), 
but this stage is not known to occur in the Tarsonemide. 
In his “ Acarina or Mites” (Report No. 108, U.S. Dept. 
Agricult. 1915, p. 109) Mr. Nathan Banks asserts that “ The 
curious [‘l'arsonemid] genus Scutacarus has a migratorial 
nymphal stage much like the hypopus of the Tyroglyphidee. 
: od 
Fig. 7. 
Acarapis woodi. 
a, last leg of female; b, ovum, greatly enlarged; c, first leg of larva; 
d, second leg of larva. 
This stage has been found on bees and ants.” This is a 
mistake, however, for it has been pointed eut by Michael 
(‘ British Tyroglyphide,’ vol. i. p. 126), and also by Enzio 
Reuter in his very excellent paper “ Zur Morphologie und 
Ontogenie der Acariden” (Acta Soc. Fennice, xxxvi. 1909), 
that the nymphal stage is suppressed in Disparipes (= Scuta- 
carus). 
The hypopial stage is always a nymph, and there is no free 
nymphal stage either in Acarapis or Tarsonemus; so that it 
is probable that the disease spreads through the adult mite. 
