CLASS I. INSECTA: ORDER 10. RHYNCHOTA. 
595 
for tlie same purpose. The Mexican Cochineal, Coccus cacti, wliicli has driven the others out 
of the field, is also a species belonging to this group. It lives as a parasite upon the Nopal, 
or Cactus opuntia — a plant very common in Central America. The commercial importance of 
this insect is shown by the fact, that in 1850 no less than two million five hundred and fourteen 
thousand five hundred and twelve pounds of cochineal were imported into Great Britain alone; 
and as about seventy thousand insects are supposed to be contained in a pound of this substance, 
we may form some idea of the numbers annually destroyed. For many years the cultivation of 
cochineal Avas entirely confined to Mexico ; but the insect has lately been introduced into Spain 
and the French possessions in Africa, with some pi'ospect of success. 
A fourth species, of great importance, is the Lac Insect, G. lacca, an inhabitant of the East 
Indies, where it feeds upon the Banyan-tree, Ficus reliffiosa, and some other tiees. To this 
insect we are indebted, not only for the dye-stnflFs known as lac-dye and lac-laJce^ but also for the 
well-known substance called shell-lac, so much used in the preparation of sealing-wax and varnishes. 
In all these cases it is only the female insects that yield the coloring matter. 
THE PHYTOPHTHIRIA. 
The greater part of this tribe is composed of Aphides or Plant-Lice, whose extraordinary history 
renders them one of the most interesting groups of insects. They are all small animals, with a 
more or less flask-shaped body, furnished with six feet and a pair of antennae, and usually with 
a pair of short tubes close to the extremity of the abdomen, from v/hich a clear sweet secretion 
exudes. Both sexes are sometimes winged, sometimes apterous ; and the individuals of the same 
species are often winged and apterous at different periods of the year. They all live upon plants, 
the juice of which they suck; and when they occur in great numbers, often cause great damage 
to vegetation. Gardeners and farmers are well aware of this. Many plants are liable to be 
attacked by vast swarms of Aphides, when their leaves curl up ; they grow sickly, and their 
produce is certain to be greatly reduced. One striking instance is presented by the Hop-Fly, 
Aphis humuli, which in England alone has often done damage to the hops to the extent of 
millions of dollars, in a single year. 
The sweet fluid which exudes from the tubular process of the abdomen of these insects is often 
in such abundance that it drops upon the leaves of the plants frequented by them, and even to 
the ground. It is well known by the name of honey-dew. Ants have a particular fondness for 
this fluid, and may constantly be seen upon trees and plants frequented by Aphides, stroking 
them with their antenna;, apparently to induce them to furnish a supply of the coveted fluid. 
From this circumstance tbe Aphides have been termed the Aufs Milch- Coios ; and they are said 
to tend them with as much eare as would be bestowed by a human farmer upon his cattle. Wasps 
also have been observed similarly engaged. The manner of propagation of these insects, which 
we have noticed in our Introduction to this Class, p. 539, is extremely curious, and has been the 
subject of immense research on the part of naturalists. 
THE CICADARIA. 
Nearly allied to the plant-lice are the Cicadaria, which include a great variety of insects, of 
which the Common Frog-Hopper of Europe, Aphrophora spumaria, is an example. This is a 
small insect, furnished with long hind-legs which enable it to perform most extraordinary leaps. 
The Tree-Hoppers of this country, Memhracidce, of which there are several species, are small, 
mostly green, and take leaps of five or six feet. 
The family of Fulgorina includes the Lantern- Flies, of which a large species inhabiting Guiana, 
the Fulgora laternaria, is said to emit considerable light in the dark. This light is produced from 
a singular prolongation of the head, which is common to this and many other species, exhibiting 
most extraordinary forms in some instances. A well-known example of the genus Fulgora is 
the F. candelaria, constantly to be seen in boxes of Chinese insects. Many of the Fulgorina are 
of a large size, and decorated with most brilliant colors ; but they are all inhabitants of warm 
climates. The European species are small, and generally very dingy in their appearance. 
The Stridulantia derive their name from the faculty they possess of producing a chirping 
