136 DISEASES OF CHOPS. 



sicm lays its eggs within the pupse of Pontia brassicce. 

 After the hatching of the eggs the parasitic larvse feed on 

 the contents of the pupse. 



Prevention. — (1) Brushing infested plants so as to dis- 

 place the caterpillars, is a means of preventing further 

 injury. Before brushing, a small quantity of crude naph- 

 thalene should be placed round each plant. This prevents 

 the caterpillars from retiirniag up the stems. (2) Dredg- 

 ings of sulphur and salt over infested plants have been 

 recommended for keeping off the attacks of this pest. (3) 

 Good cultivation and a liberal dressing of the most suitable 

 manures " has been found serviceable ; and the application 

 of liquid manure will save a crop even when badly 

 infested." 



Cure. — (1) Probably hand-picking is the most effectual 

 remedy. " Children should be encouraged to catch the 

 butterflies (as well as the caterpillars) and crush them, 

 and not be blamed for killing the 'poor little pretty 

 butterflies.' ' Handsome is that handsome does,' and the 

 converse to this is, in the same sense, equally true, 

 ' Ugly is that ugly does.' " (2) Syringing the plants with 

 weak solutions of salt, soap-suds, or lime is said to destroy 

 these caterpillars. (3) Watering the crops with a solution 

 of iron sulphate (2 per cent.) destroys the larvse of Pontia 

 brassicce, and is beneficial (as a plant-food) for cabbage 

 plants. (4) In the United States kerosene emulsion has 

 been used for destroying the larvse of the cabbage butter- 

 fly (Riley's Insect Life, vol. i. p. 27). 



The Small White Butterfly {Pontia rupee, Pieris 

 rapce) and The Green-veined White " Butterfly 

 {Pontia napi, Piens napi). The eggs of both these 

 butterflies are laid singly on the underside of the leaves 

 of cabbage plants. The larvse of these butterflies are both 



