8 
Notwithstanding these differences between the groups and species, 
there are certain points in which all agree, the more important of 
which are as follows : 
1st. In having the mouth formed for sucking, by being prolonged 
into a slender, horny, jointed tube, which arises far back under the 
breast, apparently between the front and middle legs. 
2d. In not undergoing a complete transformation, as do the beetles, 
butterflies, etc.; the larvje and pupa? being similar in form to the 
perfect insect. 
3d. In having but two joints in the tarsi or feet. 
4th. In having the antennae longer than the head, and composed 
of filiform joints. 
5th. In the fact that the winged individuals always have four 
wings. 
ath. In the fact that all live upon the juices of plants. 
7th. In their small size, no species of our country exceeding one- 
fourth of an inch in the length of the body, while many fall con¬ 
siderably short of one-tenth of an inch. 
These characters, if particularly observed, will enable the student of 
entomology, or the agriculturalist who has any knowledge whatever of 
the science, or of insect habits and characters, to distinguish plant-lice 
from all other insects. 
t 
