Another species of cochineal is the _Coccus polonicus_, which is met with in Poland and Russia, more rarely in France, on the roots of a small plant, the _Scleranthus perennis_. This cochineal is gathered in the Ukraine towards the end of June, when the abdomen of the female is swollen, and filled with a purple and sanguineous juice. The Polish kermes (_Coccus polonicus_) was formerly used very much in Europe. This product has not indeed lost all its importance in those countries where it is met with in abundance. We have now only to point out among the insects of this group the _Coccus lacca_, which lives in India on many trees, among others on the Indian fig-tree, the Pagoda fig-tree, the Jujube tree, on the Croton, &c. These last-mentioned insects produce a colouring matter known under the name of Lac Dye. They fix themselves on the little branches, getting together in great numbers, forming nearly straight lines. The bodies of many fecundated females, united together by a resinous exudation which is caused by the piercing of the bark, constitutes the matter called in commerce and by dyers by the name of Lac Dye, Shell-lac, Gum-lac, &c. Resinous lac is found in commerce under four forms:--First, the stick-lac, such as it is found concreted at the extremity of the branches whence it exudes--it is an irregular brownish crust; secondly, the seed-lac, picked off the branches and pounded; thirdly, shell-lac in scales melted down and run into thin plates, which vary in quality according to the proportion of colouring matter they contain; fourthly, thread-lac, which resembles reddish threads, and is prepared thus in India. One more word about the cochineal. The _Coccus manniparus_, which lives on the shrubs (_Tamarix mannifera_) on Mount Sinai, causes to exude from the branches it has pierced a sort of manna. The _Coccus sinensis_ produces a kind of wax which is employed in China in the manufacture of candles. IV. LEPIDOPTERA. This order of insects is known popularly by the names of Butterfly and Moth. Linnæus gave them the name of _Lepidoptera_, meaning insects with scaly wings ([Greek: lepis], a scale; and [Greek: pteron], a wing). They are to be found in great numbers in all parts of the world. All the insects contained in the order are, in their perfect state, remarkable for the elegance of their shape, the rapidity and airiness of their flight, and the multiplicity and beauty of their colours. Before they arrive at this perfect state, the Lepidoptera have to undergo three complete transformations. They leave the egg in the larva or caterpillar state; they pass next to the state of pupa, or chrysalis; they then assume, after a variable time, their final or perfect form. We will study them in their three different states in succession. THE LARVA, OR CATERPILLAR.