Insect Pests and Fungoid 'Diseases. 



409 



DIAMOND-BACK MOTH (Plutella maculipennis).ln some years 

 the caterpillars of this moth do much damage to cabbage, turnips, and 

 other cruciferous plants, by feeding on the 

 green tissue on the under-side of the leaves. 

 The caterpillars are about half an inch in 

 length, green in colour, and spindle-shaped 

 tapering to both ends. 



Treatment : Dressings of stimulating 

 manures will assist the plants to grow away 

 from the attack. Dusting the leaves when 

 they are wet, and especially the under-side, 

 with a mixture of three parts of soot to one 

 of lime will check the pest ; apply the mix- 

 ture forcibly with a powder pump. 



If not nearer than about six weeks of 

 harvesting, the crop may be sprayed with 

 arsenate of lead. 



Cruciferous weeds harbour the caterpillars and should be destroyed. 



Diamond-back Moth. 



Moth flying and Moths resting, 



Caterpillar and Cocoon ; 



all natural size. 



FLEA BEETLES (Halticce). These beetles are' often very destructive 

 to young seedlings of turnip, cabbage, and other brassicae, especially in hot 

 dry weather and on light soils. The seed leaves are eaten away directly 

 they appear above ground, and unless the seedlings are assisted or the 



weather becomes more 

 favourable it is often im- 

 possible to get a "plant." 

 Under congenial condi- 

 tions the beetles increase 

 very rapidly, and clear off 

 every particle of growth 

 as fast as it appears, so 

 that in such seasons suc- 

 cessive sowings have 

 been made three times 

 and each has proved a 

 failure. The beetles are 



very small, being only 

 1, The Turnip Flea Beetle (much magnified); about Qne tenth of an 



2, Natural length and wing expanse; 3, Natural size; 4, 5, . ,. . , , 



Kgg, natural size and magnified; 6, 7, Mine, and cuticle mch ml &^ thc ^ 



eaten away by larva; 8,9. Larva, natural size and magnified; gts of the Turnip Flea 



10, 11, Pupa, natural size and magnified. (Pliyllotreta nemorum) 



burrow into the tissues of the leaves and make holes in them, whilst those 

 of the Cabbage Flea (Haltica oleracea) feed on thc surface of the leaves 

 and do not make holes. 



Treatment : Sow only on ground which has been ploughed or dug some 

 time previously long enough for it to have settled and become mellow on 

 the surface. This will ensure a good tilth for the seed and moisture at the 



