MANUAL OF NATURAL HISTORY. 245 



SIPHON-MOUTHED INSECTS. 



The Homoptera have also been termed "plant- 

 suckers/' on account of their feeding on the juices of 

 vegetables. The Order comprises many most anoma- 

 lous forms ; some having curved horns on their backs 

 like the Centrotus and Membraces, and others being 

 provided with hollow appendages on their heads 

 as the Lantern-Flies. Some among them, as the 

 Aphides, or plant-lice, have the extraordinary fa- 

 culty of producing living young ones without a pre- 

 vious union with the other sex, which power may 

 be exercised through as many as nine generations. 

 Madam Merian has stated that the Lanthorn-Fly 

 of South America is luminous by night ; the Chinese 

 species kept alive by one of the Authors, shewed 

 however, no signs of luminosity either by night or 

 day. The insects celebrated in the songs of the an- 

 cient Greek and Roman poets (Cicada plebeia), on 

 account of the loud chirping they produce as they 

 sit among the leaves of the trees, belong to this 

 Order. The "Cuckoo-spit/' often seen on the leaves 

 of plants, is produced by the larva of Aphrophora 

 spumaria; and another species, A. Goudotii, a na- 

 tive of Madagascar, has the siugular power of emit- 

 ting a considerable quantity of clear water during 

 the greatest heat of the day. 



These insects are often highly injurious to vegeta- 

 tion, for example the American blight, Lachnus lani- 

 gcrus, and the species of Coccus that infests the vine 



