COLOUR-PRODUCING INSECTS. 47 



When preserved in a dry place, cochineal retains 

 its colour for an unlimited time. Hellot made ex- 

 periments with some dried cochineal that had been 

 kept a hundred and thirty years, and found their 

 colour as vivid as that furnished by the insects just 

 taken from the Cactus. 



The poor Indians spoken of above establish 

 their nopal plantations on cleared ground, on the 

 slopes of mountains or ravines, two or three 

 leagues from their villages, and when properly 

 cleaned, the plants are in a condition to maintain 

 the insects for three years. In spring, the proprie- 

 tor of a plantation purchases as stock a few branches 

 of Cactus tuna, laden with small cochineals recently 

 hatched, called semilla (seeds). The branches may 

 be bought for about three francs the hundred ; they 

 are kept for twenty days in the interior of the huts, 

 and are then exposed to the open air under a shed, 

 where, owing to their succulency, they continue to 

 live for several months. In August and September 

 the female insects big with young are gathered and 

 strewn upon the nopals to breed. In about four 

 months the first gathering, yielding twelve for one, 

 may be made, which, in the course of the year, is 

 succeeded by two more profitable harvests. In colder 

 climates the young insects (semilla) are not placed 

 upon the nopals until October or even December, 

 when it is necessary to shelter them with rush mats, 



