INSECTS. 145 



they gnaw througli the main root, thus quickly killing 

 the plant attacked, from which they proceed to 

 another. UsTnedies : When the caterpillars have done 

 much damage in late summer, it is recommended to 

 leave .the field alone till October, then to plough it 

 up and sow the winter grain. By putting off the 

 seed-time in this way, the caterpillars will have lost 

 their activity when the corn germinates, and the 

 winter crop will thus escape them. Besides this, the 

 preceding ploughing will bring many caterpillars to 

 the surface, where they will become the prey of birds, 

 or, if not, can be collected. Warm soils, especially 

 those manured with horse-dung, are most infested by 

 the caterpillars ; and the use of warm kinds of manure 

 should, therefore, be avoided in regions which have 

 much to fear from these insects. Where everything 

 has been destroyed, a thorough ploughing is desirable. 

 Swine may also be driven in during autumn, and will 

 grub up and devour the caterpillars. In this case, 

 sowing will take place the following spring. 



Other Surface Caterpilla/rs, which have pretty much 

 the same habits as the preceding, are those of the 

 Heart and Dart Moth (Agrotis exclamationis), the 

 Wheat Moth (A. tritici), and the TMck-bodied Surface 

 Caterpillar (A. ravida or A. crassa). 



The Cabbage Moth (Mamestra brassicce). 



Moth (Fig. 100) ; about ^^ of an inch long, span of 

 wing If inch. Fore wings shining brown, with 

 yellowish and black marbling; each patch having a 

 dark outline; a yellowish zigzag line on the outer 

 margin. Hind wings shining yellowish-grey brown, 

 A strongly developed crest in the middle line of the 

 thorax. Caterpillar (Fig. 100) : If inches, cylindrical. 

 Bright or dark green, brownish green, or greenish 

 brown. On the back a dark longitudinal stripe, divided 

 into two halves by a narrow white longitudinal line. 



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