246 MANUAL OF NATURAL HISTORY. 



and other plants in hot-houses. The Cicada septen- 

 decem sometimes appears in America in prodigious 

 numbers, and does great injury to the timber. Their 

 numbers on these occasions are so great as to break 

 the branches of the trees by their weight, and the 

 noise of their discordant drums is heard in the woods 

 from morn to eve. Another instance of the damages 

 occasioned by some of them is seen in the Sugar-cane 

 Fly, Delphax saccharivora, so injurious to the West- 

 Indian plantations. On the other hand, the fine 

 white wax manufactured by the Chinese, and highly 

 prized in the East Indies, is obtained from species of 

 Hata in an immature state. Cochineal is produced 

 from the Coccus cacti ; the "scarlet grain" of Poland, 

 also a valuable dye, from Coccus Polonicus ; lac is 

 derived from Coccus lacca ; the Coccus ceriferus 

 is used in the production of a white wax; and 

 the manna of Mount Sinai is owing to the punc- 

 tures of Coccus manniperus on the Tamarix man- 

 nifera. 



IX. ORDER. SIPHON-MOUTHED INSECTS (Homoptera). 



Wings four, entirely membranous, deflexed ; an- 

 terior the largest, not overlapping in repose ; anten- 

 nae short, setigerous ; mouth produced, arising from 

 under hind surface of head; mandibles and max- 

 illae setaceous, enclosed in labium, which forms a 

 jointed siphonal canal ; body convex ; tarsi not more 

 than 3-jointed. Pupa active, semi-complete. Subsist 

 upon vegetable juices which they pump up by means 

 of their siphon-like mouth. 



