Rhynehart — Life-History and Bionomics of the Flax Flea-Beetle. 531 



because they are less capable of outgrowing and overcoming the attack, suffer 

 more than those in strong, vigorous brairds. It follows, iherefore, that any- 

 thing which tends to encourage the strong, vigorous growth of the seedlings 

 is, indirectly, a preventive measure against the chances of extensive damage. 

 Hence the importance of using only seed of first-class germiuatint; capacity. 

 and of sowing it only on suitably prepared and properly manured fields. 



As already suggested, the time of sowing may have a considerable 

 influence on the intensity of an attack ; and, as the earlier brairds often suffer 

 considerably, while those appearing later practically escape, it is evident 

 that very early sowing is not desirable in districts where the flax flea-beetle 

 is prevalent. It is certainly not desirable to sow isolated fields early, but 

 rather should it be the aim to get all the flax in a particular district sown at 

 approximately the same time, as the beetles, when spread over a considerable 

 area, are less liable to cause serious damage in any particular field. 



The sowing of small jireas of flax at least one week earlier than the main part 

 of the crop, and using these areas as traps on which to catch beetles attracted 

 thereto, suggests itself as a method whereby large numbers may be destroyed. 

 The destruction of the beetles is best achieved by sweeping over the seedlings 

 a sack or light board, coated with tanglefoot or other sticky material, in 

 which the disturbed beetles are caught and held. Such operations give best 

 results when done during bright sunlight (when the beetles jump most 

 readily from the food plants), and in such a manner as to facilitate their 

 jumping against the sticky board when disturbed. The sweeper should be 

 regularly cleaned, and fresh coats of the sticky material applied. As the 

 beetles appear to be attracted to white-coloured areas, the sweeper should be 

 as white as possible, and, even when left lying in the vicinity where beetles 

 abound, these sweeping boards may trap considerable numbers. 



Further destruction may be effected by the thorough cultivation of the 

 trap plots in late June, which kills any eggs laid during May and early June, 

 and any larvae newly hatched therefrom. 



Excellent results have been obtained from the use on attacked seedlings 

 of light dressings of stimulating manures before the attack has extensively 

 developed. Thus, a dressing of not more than | cwt. of nitrate of soda per 

 statute acre has been found highly beneficial when applied to attacked 

 brairds. 



Trials of various possible remedies were made at Coleraine during the season 

 1921. These consisted of dressings of the seed, and dusts and sprays applied 

 to the seedlings. Some of the latter were intended to act as repellents by 

 creating a noxious smell, or otherwise making the seedlings distasteful to 

 the beetles ; others were intended to act as poisons ; while a few were 



SOIENT. PBGC. R.D.S., VOL. XVI, NO. XXXIX. 3 I 



