53 
Acarus, or Red Spider. — The Spider 
infesting the Apple tree is similar to those which 
attack the Gooseberry bush, but rather less in size, 
and its process differs materially. The first ap- 
peai’ance of these animals on the tree, in the 
spring, is about the beginning of May, and, like 
several of their genus, they are so diminutive 
as to require the aid of a microscope to see 
them distinctly. They chiefly feed on the under- 
side of the leaf, and sometimes in hot dry wea- 
ther on the upper surface. They appear not to 
be furnished with w'ebs like those on peach and 
nectarines. About the latter end of June, and 
beginning of July, the first brood leave the tree, 
to return no more, after depositing their eggs 
on the underside of the leaf. I have seen upon 
an average about twenty-five eggs upon one leaf. 
In the course of a week a second cletch is pro- 
duced, which, if the weather proves hot or dry, 
deposit their eggs at the latter end of July, and 
leave the tree. The eggs, about the middle of 
Aus-ust, issue forth a third cletch, w'hich remains 
till about the middle or latter end of September, 
when, after depositing their eggs, they leave the 
tree, as all the former broods, and die. But 
how remarkable it is that the last brood, like 
one species of the Aphides already described, 
quit the leaf contrary to the practice of the former 
brood, and place their eggs on the branches, spurs, 
&c., as though it were prognosticated that the 
period w'as near when their former residence 
