268 



HEMIPTERA-HOMOPTERA. 



The aphis on the trees may be killed by spraying with fwce 

 with paraffin emulsion, or better still, tobacco wash. The 

 ground form may be kept from ascending by banding with 

 Tanglefoot. In Australia and South Africa apples are only 

 grafted on Northern Spy or Majetin stock ; the roots of these 

 are immune. 



Fio. 153.— Plum Aphis (Aphis pruni). 

 1, Viviparous female ; 2, ovigerous female. (Whitehead.) 



Numerous other plant-lice attack crops and fruit, among 

 which we may mention the Corn Aphis (Macrosiphum 

 granaria) ; the Cabbage Louse (A/ihis fo'a.ssjVv/), which crinkles 

 up the cabbage leaves, forming a mealy mass of lice ; the 

 Plum Louse (A. pnini) (fig. L53), curling up the leaves of 

 the plum; the Cherry Louse [Mij:.ii^ cerasi) (fig. 151), which 

 collect on the shoots of cherries, forming blaclc groups and 

 discolouring the fruit with tlieir excrement ; the Currant 

 Aphides {Rho^iahMi'iilmm lacfnni'), A'c. All can be destroyed 

 by the same washes, and need no further comment here. 

 (T7r?e Appendix II,) 



