TURNIP SAWFLY ; SURFACE CATEPiPILLARS. 



199 



plant, and destroy many of the caterpillars by washing them 

 off the leaves into the wet soil. 



In all attacks on leafage it is of the utmost importance to 

 keep up the strength of the plant ; the damage done is by the 

 grubs destroying what for its own vegetable uses are in fact 

 its breathing and digestive organs. It cannot live without 

 its leaves, and if a larger portion of these are eaten off each 

 day than is replaced by growth, it fails just in that proportion. 

 By the application in moist weather of nitrogenous or ammo- 

 niacal manure, or by watering with liquid manure in drought, 

 a plentiful supply of food is brought to bear at once, and thus 

 we may possibly tide the plants over the difficulty and save 

 the crop within the bounds of remunerative outlay. 



Where a Turnip field has been infested during autumn, it 

 is desirable to work the surface with a scarifier or grubber so 

 as to turn up the earth cocoons w^ith their contents to the 

 surface, where a good proportion of them would be destroyed. 



Surface Caterpillars : Caterpillars of the Turnip or Dart 

 Moth, Arjnitia sajctiun, Ochsenbeimer ; also of the Heart- 

 and-Dart Moth, Agrotis exclamationis, Liuu. 



Common Dart Moth ; 1, moth; 2, caterpillar. 



The term of "Surface Caterpillars" is applied to various 

 kinds of moth-caterpillars or grubs, which, like the so-called 

 " Turnip-grub," the caterpillar of the Turnip or Dart Moth, 

 live and feed near the surface of the ground. There are many 

 kinds, but those of the Dart and the Heart-and-Dart Moth, 

 resemble each other so much, both in their appearance and 

 habits, that they may conveniently be placed under one 

 heading. 



They do an enormous amount of damage, especially to 

 Turnips ; but the amount of prevalence of the infestation is 



