TURNIP "FLY" OR FLEA " 273 



from which, in about twelve days, the perfect beetles 

 come and proceed to attack the Turnip or other 

 Brassica plants. In dry and hot seasons or under 

 suitable conditions for increase as many as six genera- 

 tions may be produced during the summer. 



The Turnip Fly thrives in dry, dusty and cloddy 

 soil, and in a dry summer causes much harm to Turnip 

 plants as they cannot grow away from its attacks. 

 Directly the leaves come from the seeds, the young 

 plants are eaten or riddled with holes (G, p. 27 8) and can 

 make no further progress, or, if they continue to grow, 

 they are often so weakened as to be practically worth- 

 less. In times of drought irretrievable mischief is done, 

 sowing after sowing being cleared off by the beetles in 

 rapid succession. The main and most dangerous 

 attack is when the plants are just starting and until 

 they are fairly in " rough leaf," yet when the weather 

 proves dry after the plants are in second leaf, the tops 

 are often so much bitten by the beetles and the mining 

 of the larvae that the plants do not make good roots. 

 Even when roots are formed and are of some size, late 

 generations of beetles stick to them, in some seasons 

 to the end of September. The flea beetle not only 

 attacks Turnips and Swedes, but is often very de- 

 structive to Rape, Mustard, Kohl-rabi, Cabbage and 

 other Brassicas, or cultivated Cruciferous plants. It 

 also lives on such weeds as Charlock, Shepherd's Purse, 

 and Jack-by-the-Hedge. 



Two other species of flea beetles are more or less 

 injurious to Turnips and other plants of the same 



18 



