S96 



MALFOllMATIONS AND DISEASES 



able to the production of Hemiptera. 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 belongs also the 

 CJiermeSj one species of which, Ch. cacti, produces the Cochi- 

 neal ; a second is found upon the Oaks of the South, and 

 produces the French Cliermes ; a third kind, Ch. polar icuSy 

 nestles in the roots of the Scleranthus perennis ; and all the 

 three kinds produce colouring matter. To this order belong 

 the Cocci, which fix themselves almost immoveably, and quite 

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

 of the plants, with their proboscis, which springs from their 

 breast. We are acquainted with two species. Coccus hesperi- 

 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 shape 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-Willows. 



The small Thrips pJiysapus 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 ohtusiflorus, and acutiflorus, are 

 disfigured by the puncture of the Livia juncorum, and the 

 mischief done in corn fields by the Acluta gryliotalpa, is known 

 to every person. 



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 Bombyx 

 dispar, chrysorrhwa, coeruleocepliala, Hispaniola, processio- 

 nea, Neustria, and of Noctua hrumata. The caterpillars of 

 Papilio Cratagi, Brassicce, Rapa, and Napi, suck princi- 

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

 Bombyx Pini, Hadena piniperda, and Phala,na geometra 

 piniaria ; and in Oak woods, the larvse of Bombyx monachal, 

 and Noctua brumata, occasion very great devastation. The 



