46 INSECT PESTS 



M. cBneus is often found on mustard in company with 

 the last-mentioned insect, and does similar damage, 

 eating the flowers and so reducing the yield of seed. It 

 is only one-twelfth of an inch long, varying in colour 

 from black to dark green or violet, with a brassy gloss, 

 quite a neat little thing. The larva is yello\^dsh white 

 or pale grey. (See Plate 9.) 



Both beetles lay their eggs on the opening buds, on 

 which the larvae feeds, afterwards dropping on to the 

 soil to pupate. 



The best treatment consists in beating or shaking out 

 the adults into vessels containing paraffin, although 

 equally good work can be done by boys with butterfly 

 nets, shaking the flower-heads free of beetles ; the nets, 

 when a quantity of beetles has thus been obtained, being 

 shaken into boiling water. The nets may be used wet, 

 as this prevents the insects from crawling out. 



In badly infested fields it is, however, desirable to 

 plough in the whole crop deeply, so as to bury the eggs 

 before they can come to maturity. The eggs are yellow, 

 like the flowers, and as a consequence difficult to see. 



We must now turn our attention to field root-crop 

 pests. Turnips and Swedes will answer this purpose, 

 the Beet and Mangold pests I shall deal with in the 

 next chapter. Turnips and Swedes seem to be the 

 special quarry of destructive insects, almost as much 

 so as the cabbages of the kitchen garden. We have 

 once more both beetles and moths, to which must how- 

 ever be added aphides, saw-flies, and two-wing flies. 

 Turnips suffer the most as a rule, and it has even been 

 noticed that where a bad attack on this crop has occm'red, 

 swedes are more resistant, if not altogether immune, 

 although growing close by. 



The damage done to turnips and swedes by aphids 

 and two-wing flies is almost negligible compared with 

 the other three types of insects mentioned, and their 

 consideration may be left to be dealt with under other 



