RHYNCHOTA. 
(Hemiptera).—Bugs. 
T wo pairs of wings, theupper hyaline at theapical half only or both hyaline 
throughout, with few veins. Mouth-parts suctorial. Antennae simple. 
Metamorphosis simple, the wings developed outside the body, the 
nymphal and imaginal stages little differentiated and of almost equal 
duration and importance in most forms. The order includes only 
insects whose nourishment is the sap of plants, or the blood of 
vertebrate animals or insects obtained by suction. 
The most characteristic feature of these insects is the suctorial beak, 
in which the lower lip (labium) forms a sheath for the mandibles and 
maxillae which are the actual sharp piercing organs; applying the tip of 
the “beak” to the plant or insect, the setae are pushed in, the “beak” 
tself not entering the tissues but only the setae ; the semi-tubular labium 
is partly covered at the base with the more or less elongated upper lip 
(labrum). 
The order is a large and distinct one, but it includes a greater variety 
of forms than perhaps should be included in the limits of one order. It 
is commonly divided into two sub-orders Heteroptera and Homoptera; 
these may be defined on two characters, first, that the tegmina are 
thickened at the base or are of the same texture throughout ; second, 
that the head does not touch the coxse or is so indexed as to be in 
contact with the front coxse. The two series are in the main distinct 
and there is good reason to separate the first as a distinct order, the 
second as not necessarily one but perhaps two or three orders. We 
treat them as forming three sub-orders under one "order. We have 
explained below the grounds for treating Phytophtliires as a distinct 
sub order :— 
