HEMIPTERA. 185 



of plants. Some are valuable for the rich red colour they furnish to 

 the art of dyeing. Further researches on these Insects might even- 

 tuate in the discovery of otheis which would prove of similar utility. 

 Geotfroy divides the Gallinsecta into two genera, Chermes and 

 Cocus. Reaumur designates the latter by the name of Progall- 

 Insecte. 



C. adonidum, L. Body almost rose-coloured and covered 

 with a wliite farinaceous dust; wings and caudal setae of the tail 

 white; sides of the female furnished with appendages, the two 

 last of which are the longest, and form a sort of tail. She en- 

 velopes her ova with a white and cottony substance that serves 

 for a nest. Naturalized in our green-houses, where it does much 

 injury. 



C. cacti, L. ; Thier de Menouv., De la Cult, du Nop., et de la 

 Cochen. Female of a deep brown covered with white dust, flat 

 beneath, convex above and bordered ; the annuli are tolerably 

 distinct, but become obliterated at the epoch of production. The 

 male is of a deep red, with white wings. 



This Insect is cultivated in Mexico, on a species of Opuntia, 

 and is distinguished by the name of Mesteque — fine cochineal, 

 from another very analogous, but smaller and more cottony, or 

 the Sylvestre. It is celebrated for the crimson dye it furnishes, 

 which, by being combined with a solution of tin in nitro-mu- 

 riatic acid, produces a scarlet. It is also from this Insect that 

 we obtain carmine. It is one of the richest productions of 

 Mexico *. 



C. polonicm, L. ; Breyn.,*E, iv, c, 1731; Frisch, Insect., II, 

 5, p. 6. Female russet-brown, resembling a granule, and at- 

 tached to the roots of the Scleranthus perennis, and some other 

 plants. Previous to the introduction of cochineal, this Insect 

 constituted an important object of commerce. The colour it 

 produces is of the same tint, and almost as beautiful as that of 

 the preceding species. It is still employed in Germany and 

 Russia. 



C. ilicis, L. ; Reaum., Insect., IV, v. The female, both in 

 size and shape, like a pea. It is of a dark violet or prune-colour, 

 covered with Avhite dust. Found on a species of Oak in Pro- 

 vence, Languedoc, and southern parts of Europe. It is used in 

 dyeing crimson, particularly in the Levant and Barbary. Scar- 

 let was also obtained from it previous to the general introduction 

 of the cochineal from Mexico. It is still used in medicine f. 

 A certain species that inhabits the East Indies forms gum lac. 

 Another enters into the composition of a peculiar bougie em- 

 ployed in China J. 



* See Humboldt's Travels. 



t For the other species see Reaumur, Linnoeus, Geoffrey, De Geer, Latreille, and 

 Olivier, Encyc. Method., article Cochenille. For the C. cacti, see a Literary Gazette, 

 printed at Mexico, 5th February, 1794. M. Bory St. Vincent— Annal. des Sc. Nat., 

 \ III, 105— informs us that experiments had been made at Malaga, in Spain, with 

 a view to introduce the cultivation of this latter species, and that they succeeded. 



X Doctor Virey, Journ. CompK-ment. des Sc. Med., X, has published some new 

 observations respecting this production. 



VOL. IV. O 



