176 ENTOMOLOGY 



employing both for a long time in his practice, gave the 

 preference to our native fly. It however cannot be col- 

 lected here in sufficient quantities to supply the demand, 

 and consequently is not so much used as the foreign in- 

 sect. The active virtues of the Blistering-fly, depend 

 upon the existence of a principle, which has obtained the 

 name of Canlharidin. 



The second order, is named Ifcmiptera, from emisu, 

 the half, and pteron, a wing. Tiie outer wings of this 

 order, are semicoriaceous : they are not so strong as those 

 of the first order, but more so than the remaining orders. 

 This includes the cockroach, locust, lantern-fly, wa- 

 ter-scorpion, bug-plant, louse, &c, &.c. The 1st genus, 

 as arranged by Linnaeus, is the cockroach : this is an 

 extremely troublesome animal, not only destroying our 

 articles of food, but in many cases, our garments and 

 books. By the ravages of the Aphis, or plant-louse, 

 whole crops are often destroyed ; our esculents arid valu- 

 able plants; our fruit trees, as well as those of our woods, 

 are all injured by this insect : by suction, it abstracts 

 from the tender shoot its nutriment, and blasts the leaf 

 by its peculiar secretion. This secretion is sometimes 

 enormous ; and not only by its quantity completely encases 

 the plant, but by its saccharine nature, affords a resting 

 place for noxious insects. The cocci also, which look 

 like protuberances upon the stalks of plants, do consid- 

 erable injury by drawing off the sap, and thus destroying 

 life. To refer to any more genera of this order, would 

 be needless. It is time to turn to those of this order 

 which are of value to us. In speaking of the advan- 

 tages derived from many insects of the preceding 

 order, I referred to some which kept other species in 

 check, by subsisting upon them. In this order we find 

 the Mantis tribe ; those whose peculiar appearance has 

 given the idea of sanctity, one of the most ferocious tribes 

 of insects, even carrying there animosities so far as to 

 destroy each other. But to the coccus are we to look, 

 as the most valuable genus of this order, By a species 

 of this genus, is produced the Pe-la, or white wax of 

 China. The Chinese cherish these insects by stocking 

 some species of trees with them. This secretion begins 



