Sept. 189o.] 



INJL^KIOUS INSECTS AND FUNGI. 



175 



The Turnip "Fly" or "Flea" {PJiyllotreta nemoriim). 



1. Beetle much magnified ; 2, length and wing expanse ; 3. natural size ; 4, 5, egg, 

 nat. size and mag. ; 6, 7, mine, and cuticle eaten away by larva ; 8, 9, larva, oat. 

 size and mag. ; 10, 11, pupa, nat. size and mag. 



The Turnip Fly or Flea is a small beetle which thrives in dry, 

 dusty, and cloddy soil, and in dry seasons 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 

 riddled with holes and can make no further progress ; or, if they 

 continue to grow, they are in most cases so weakened as to be 

 practically useless. In conditions favourable to the propagation 

 of the beetles, they increase with wonderful rapidity. Genera- 

 tion succeeds generation, clearing off every particle of growth 

 as it appears. The beetles do not flourish in showery weather, 

 and as this suits the turnip plants ; it is only in times of drought 

 that irretrievable harm is done. In such seasons, turnips have 

 often been sown three times, and each crop has been successively 

 cleared off. In 1881, enormous losses were sustained by farmers 

 in many parts of England and Scotland. These were so great 

 and so widespread that an inquiry was instituted by the Royal 

 Agricultural Society of England, and in the Report of the Society, 

 compiled by Miss E. Ormerod, it is stated that, in very many 

 cases, turnips and swedes were sown three times without 

 any crop resulting. The losses, as estimated in this Report, for 

 seed, expenses of sowing, and re-sowing, in the season of 1881, 

 amounted to o^er half a million of money, quite independent of 

 the enormous losses and inconveniences sustained, in many parts 

 of the kingdom, from the entire failure of the turnip crop. 



Though the main and most dangerous attack of these beetles 

 is undoubtedly when the plants are just starting, and until they 

 are fairly in strong " rough leaf," it is by no means unusual in 

 periods of drought to find that even if the plants manage to 

 grow away from the first onslaughts, they are so steadily and 

 constantly beset by the insects, and their leaves are so much 

 bitten, that they never make good roots. When the roots are 

 formed, and are of some size, late generations of beetles pertina- 

 ciously stick to them, in some seasons even until September. 



