INSECTS. 115 



most, or even all, of the plants in a rape field are 

 withered; on poor soil the whole crop must he at 

 once ploughed up ; hut on fertile soil the plants often 

 develop much better than one would believe. Plants 

 whose stem has been killed in the winter while still 

 short may develop a few (3 to 5) branches from buds 

 situated near its base, but these usually remain small, 

 and do not yield a large crop. The beetles, appearing 

 in spring, lay their eggs on the lower leaf-stalks of the 

 rape, either on the old plants of winter rape or young 

 plants of summer rape. In the latter case the summer 

 rape is quite spoilt in the same way as the winter 

 rape during the previous winter. In the former case 

 the larvae eat out the lower part of the leaf-stalks, 

 and make their way into the stem, hollowing it out 

 at a definite spot in such a way that it is no longer 

 able to hold itself up, especially when the shoots and 

 seeds develop. The stems bend and become kneed, 

 sometimes to such an extent that the rape-field looks 

 as if persons or cattle had been running about in it in 

 all directions, and treading everything down. Mean- 

 while the larvae bore their way out of the stem, and 

 become pupae in the soil. In late summer the beetles 

 appear, and once more lay their eggs on the leaf- 

 stalks of the winter rape. There are, therefore, two 

 generations annually. Remedies : Never sow summer 

 rape after winter rape which has been destroyed by 

 the beetle and ploughed up. Temporary limitation 

 of rape culture. 



The Cabbage Flea Beetle {Raltica oleracea), one- 

 fifth to one-sixth of an inch long, longish oval, dark 

 green, metallic sheen. The hind legs do not possess 

 the peculiar features of the rape flea beetle (p. 114). 

 Larva one-fifth to one-fourth of an inch long, greyish 

 black, with bristly hairs, and with two rows of shining 

 black warts. The beetles attack, in the spring, chiefly 

 cabbage, rape, radishes, horseradish ; but do not spare 

 other plants (e.g. peas and beets) as well. Seedlings 



