572 Insects. 



When the Mexicans have gathered the Cochineal In- 

 sects, they put them into holes in the ground, where 

 they kill them with boiling water, and afterwards dry 

 them in the sun; or they kill them by putting them 

 into an oven, or laying them upon hot plates. From 

 the various methods of killing them arise* the different 

 colours in which they appear when brought to us. 

 While they are living, they seem to be sprinkled over 

 with a white powder, which they lose when the boiling 

 water is poured upon them, but preserve when killed in 

 an oven. Those dried upon hot plates are the best. 



The quantity of Cochineal annually exported from 

 Mexico and South America is said to be worth more than 

 five hundred thousand pounds sterling a vast sum to 

 arise from so minute an insect ; and the present annual 

 consumption of Cochineal in England has been esti- 

 mated at about one hundred and fifty thousand pounds 

 weight. The Mexicans think so highly of their trade 

 in this insect, that the republic has adopted the nopal- 

 tree as part of its arms. 



It is for dyeing scarlet that Cochineal is chiefly in 

 demand ; but, although a peculiarly brilliant d}^e is now 

 obtained from it, this substance gave only a dull crim- 

 son colour until a chemist of the name of Kuster, who 

 lived at Bow, near London, about the middle of the 

 seventeenth century, discovered the art of preparing it 

 with a solution of tin. Cochineal, if kept in a dry place, 

 may be preserved without injury for a great length of 

 time. An instance has been mentioned of some of this 

 dye, one hundred and thirty years old, having been 

 found to produce the same effect as though it had been 

 perfectly fresh. 



THE PLANT LOUSE, OE GEEEN FLY. (Aphis.) 



THE APHIDES are sometimes viviparous, and at other 

 times oviparous, according to the season of the year. 



