418 The Profitable Culture of Vegetables. 



as nitrate of soda, to enable them to grow away rapidly and so escape 

 serious damage. 



Leaves showing injury and any plants very stunted or killed should be 

 collected and destroyed ; they should not be fed to stock or any larvae 

 present may develop into flies. 



Paraffin emulsion sprayed on the foliage will keep the flies away. 



Weeds liable to attack by this fly, such as thistle and dock, must be kept 

 down. 



CABBAGE APHIS (Aphis brassicce),- This aphis is of a greenish blue 

 colour, and is common to all the members of the cabbage family, attacking 

 them on the undersides and in the folds of the leaves. It is most prevalent 

 in the latter part of a hot dry summer and in the autumn. It increases 

 very rapidly, and being protected by a waxy covering which throws off 

 spray, it is more difficult to eradicate than most aphis. 



Treatment : When the season is unusually hot and dry it is a wise 

 precaution to take preventive measures to prevent any considerable infesta- 

 tion, and whilst this applies to any brassica crop it is especially necessary 

 with Brussels sprouts, as these are rendered unsaleable when badly in- 

 fested with aphis. The best spray for the purpose is paraffin emulsion, 

 and several applications may be necessary, but spraying must not be done 

 when the crop is nearly ready for gathering. In case of a bad attack 

 at such a time it is scarcely practicable to do anything beyond removing 

 and destroying the worst infested leaves. 



CABBAGE BUTTERFLIES and CABBAGE MOTH. The cabbage tribe 

 is subject to attack by the caterpillars of three kinds of butterfly the Large 



White (Pieris brassicce), 

 the Small White (Pieris 

 rapce), and the Green 

 Veined (Pieris napi) ; 

 also by the caterpillar of 

 the Cabbage Moth 

 (Mamestra brassicce}. 

 Both butterflies and 

 moth deposit their eggs 

 on the leaves, especially 

 those of cabbages ; these 

 eggs hatch out in six or 

 seven days, and the 

 caterpillars at once begin 

 to attack the leaves; 

 when on cabbage they 

 eat their way to the 

 heart, disfiguring and 

 often completely spoiling 

 1 , Large White Cabbage Butterfly ; it, besides covering the 



2, Eggs; 3, Caterpillar; 4, Chrysalis. leaves with a disgusting 



