296 ?.IALroi{MATIONS AND DISKANES 



able to the production of Heiiuptera. They are accordingly 

 produced in hot-houses to which little air is afforded. Cab- 

 bage plants are less subject to their depredations in the open 

 field than in gardens. To this family belong-s also the 

 ChervieSj on.e species of which, Ch. cadi, produces the Cochi- 

 neal ; a second is found u})on the Oaks of the South, and 

 produces the French Chcrmcs ; a third kind, Ch. polai^icus, 

 nestles in the roots of the SclerantJms ijerennis ; and all the 

 three kinds produce colouring matter. To this order belong 

 the Cocci, w hich fix themselves almost immoveably, and quite 

 flat, upon the plants of our hot-houses, and suck out the sap 

 of the plants, with their j)roboscis, which springs from their 

 breast. We are acquainted with two species. Coccus hespei'l- 

 dum and C. adonidum. There is also the Cercopis spumaria, 

 which sucks the juices of Grasses, and especially of Willows, 

 and gives it out again in the sha})e of foam : it is called 

 Cuckow's Spittal, — and when, as sometimes happens, it falls 

 down in drops, it has given rise to the expression of Drop- 

 ping-Wiilow s. 



The small TJirips physapus is also very common in the 

 flowers of many plants, and perhaps assists in the impregna- 

 tion, but frequently, also, it gnaws the germen. 



The flowers of Juncus ohtus'iflorus, and acutiflorus, are 

 disfigured by the puncture of the Livia juncorimi, and the 

 mischief done in corn fields by the Acheta grylloUdpa, is known 

 to every person. 



427. 

 The innumerable crowds of butterflies, particularly in the 

 caterpillar state, are exceedingly destructive to plants. The 

 greatest enemies to fruit-trees are the caterpillars of Bomhyx 

 d'lspar, chrysorrhaa^ caerultocephala, Hiapaniola, processio- 

 nea, Neustrla, and of Noctua brumata. The caterpillars of 

 Papilio Cratagi, B?'assica, Rapa, and Napi, suck princi- 

 pally the garden vegetables. In Fir Avoods, the larvae of 

 Bomhyx Pini, Hadena piniperda, and Phalcena geometra 

 pmiaria ; and in Oak woods, the larva? of Bomhyx nw^iacha, 

 and Noctua brumata, occasion very great devastation. The 



