Rhynehart — Life-History and Bionomics of the Flax Flea-Beetle. 533 



destruction of the insects with a poison wash sprayed on the seedlings more 

 remote, since new foliage untouched by the poison wash is rapidly produced. 

 Therefore, when considering likely useful washes, the possibility of improving 

 the adhesive properties of well-known poisonous substances by the addition 

 of agents reputed to impart such properties was primarily considered, as 

 was also the possibility of combining a wash which, as well as being 

 poisonous, had a deterrent effect. Different strengths of Bordeaux mixture 

 were used alone, and also with the addition of («) casein, (5) flour paste, and 

 (c) soft soap, to test the comparative adhesive and spreading properties of 

 the resulting mixtures. These properties were not, however, observed to be 

 appreciably increased by any of these substances. Bordeaux mixtures, with 

 the addition of (a) lead arsenate, (b) 98 per cent, nicotine, (c) lead arsenate 

 and flour paste, and {d) lead arsenate and soft soap, were also tried. The 

 last-named mixture scorched the seedlings, but not beyond recovery. In all 

 the other cases no appreciable damage to the seedlings could be detected. 

 Other washes used were lead arsenate, lead arsenate-paraffin emulsion, 

 potassium chromate, potassium sulphide. Burgundy mixture, and copper 

 sulphate solution alone. 



Lead arsenate spreads and adheres very indifferently to flax seedlings, 

 while lead arsenate-paraffin emulsion would appear to be little better ; 

 moreover, the latter scorched and browned the seedlings to a considerable 

 extent. Both potassium sulphide and chromate are poor spreaders, and 

 adhere badly, so that they are unsuitable for use alone on flax. The former 

 was intended to neutralize the supposedly attractive stimulus emitted by the 

 brairding seedlings, but it did not appear to possess that property. 



The slight infestation of beetles during the season is to be regretted from 

 the point of view of testing possible remedies, and little can be said regarding 

 the usefulness or otherwise of many of the washes used. Bordeaux mixture, 

 however, gave indications of acting as a deterrent to the influx of beetles on 

 plots to which it was applied alone, or in conjunction with lead arsenate or 

 nicotine. 



A Bordeaux mixture containing about 1|- per cent, of free copper sulphate 

 was also tested, and this, besides having the deterrent properties of the others, 

 had the effect of destroying weeds such as Spurrey {Spergula arvensis) and 

 Charlock (Sinapis arvemis), both of which were present to a considerable 

 extent; the flax seedlings were not, however, injured. Next season it is 

 hoped to continue experiments dealing with probable preventive and remedial 

 measures. 



Finally, it should always be borne in mind that to wage war on anything 

 about the farm that is calculated to afford shelter for the beetles during the 



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