Rhynehart — Life-Hisiory and Bionomics of the Flax Flea-Beetle. 635 



7. The adults hibernate in sheltered positions underneath grass, weeds, etc., 

 and in cracks and crevices in the soil or in ditches and walls, during the 

 winter, and come out in spring, when the weather becomes favourable. 



8. The females lay eggs in the soil in which flax is growing from early 

 May to late June. These hatch in sixteen days, giving rise to minute larvae, 

 which bore into and feed on the roots of the flax plants, but do not appear to 

 cause any appreciable hindrance to growth. 



9. The feeding larval life occupies about twenty-seven days, during which 

 time the larvae increase in size and become slenderly elongated in shape. 

 When fully fed the larvae leave the root-tunnels and go into the soil, where 

 they transform to pupae in crude cocoons of earth. 



10. The pupa is small and stout, soft and white, and from it the adult 

 emerges after twelve days. Emergence reached a maximum in Co. Derry 

 about the 25th July, 1921, which was a month earlier than that observed the 

 previous season. 



11. The complete life cycle from egg to adult is passed in about sixty 

 days, and there is only one generation annually. 



12. The species is particularly free from the attacks of internal parasites, 

 and no serious natural enemy has been observed. 



13. Preventive measures consist of the production of strong, vigorous 

 growing brairds by the employment of suitable cultivation, seed, and manure ; 

 and in the destruction or removal of all likely hibernation quarters, especially 

 near fields which recently grew a flax crop. Early sowing of isolated fields 

 should be avoided. 



14. The stimulation of attacked seedlings by the application of a light 

 dressing of nitrate of soda has proved beneficial. 



15. Experiments carried out in Co, Deny during the 1921 season indicate 

 the possibility of the use of Bordeaux mixture as a deterrent. Owing, 

 however, to the very slight infestation that season, the information gained 

 from trials on possible remedial sprays is not sufficient to warrant the 

 recommendation of any particular treatment, and further trials are very 

 necessary and desirable in this connexion. 



