1878. | On the Transformations of the Red Mites. Igi 
are most often noticed, presenting to the ordinary observer the 
appearance of a bright red oblong-ovoid body growing from the 
wing. They are so firmly attached by the mouth, so immovable, 
and with the legs so short and hidden, that persons unfamiliar 
with their true nature might easily mistake them for some natural 
growth or excrescence. That they are often so numerous as to 
‘weaken and kill their victim, reports clearly prove. 
In due time these swollen bodies let go their hold and drop to 
the ground where, clumsily and with difficulty, they crawl under 
_ the first shelter afforded by some bit of loose earth, or a stone. 
Here they remain quiet for two or three weeks, gradually swell- 
ing and changing form. During this change the pupa state is 
assumed, but not by shedding any skin as do true insects in going 
through their transformations. New legs, feelers and mouth- 
parts form under the old skin, which, with its now useless legs, 
distends so as barely to cover the new parts, which are all 
appressed to the body very much as in the pupa of a beetle. 
(Fig. 24.) Finally both the distended larval skin and the new one 
that incases the pupa burst, and release a creature quite different 
from the former Astoma—in fact, none other than the 8-legged 
Trombidium. (Fig. 2c.) We thus see that from the time this mite 
hatches, through all its growth and changes, but one molt takes 
_ place. The mature form passes the winter in the ground, and is 
active whenever the temperature is a few degrees above freezing 
point. ! 
Only two species of the genus Trombidium have been described 
in America, viz: scabrum Say, and sericeum Say? The descrip- 
tions in both cases are brief, and lacking in structural details and 
in measurements. The locust mite under consideration has been 
hitherto referred to sericeum, but the characteristic polished anal 
~ plate precludes the reference, and we define it under the name of 
locustarum. Since the time when it was established by Fabricius, 
evidently on the characters of the European T. holosericum, the 
genus Zrombidium has been greatly modified by different authors. 
_ The species have been variously arranged according to relative 
length of legs, position of eyes, divisions of the body, etc. As 
restricted at present, the genus is thus characterized. Abdomen 
’ swollen, especially in front where it is broadest; cephalo-thorax 
small and narrow, with two eyes, superior and barely raised; 
$ Jouri. me Nat. Sc. Phil. 11, 1821, p. 70. 
