534 Scientific Proceedings, Royal Duhlin Society. 



winter is, indirectly, a preventive measure against future attacks. Hence 

 all grass and weeds present on fields from which a crop of flax has recently 

 been removed (besides that occurring on ditch-backs and dry banks beside or 

 near such fields) should be destroyed or grazed bare by stock, for by so doing 

 the beetles are deprived of many suitable places for hibernation, and are, 

 consequently, exposed bo greater risks during the winter months. 



It is the writer's opinion that the practice of sowing grass seeds with the 

 flax, common iia some districts, facilitates the perpetuation of this pest, 

 because such a pra^^tice providesfor the needs of the beetles at critical periods. 

 Thus, aftm- the flax has been pulled and removed, they have ample suitable 

 food in the young grasses and clovers, and, later, sufficient protection for 

 hibernation is aftbrderl practically anywhere in the field. 



Thorough cultivation after the removal of the flax, besides removing food 

 and hibernation quarters, is desirable from another aspect. If, as was the 

 case iji 1920, the brood of beetles has not emerged at the time of pulling the 

 flax, many of the soft, delicate pupae in the soil will be destroyed or brought 

 to the view of birds by such processes. These cleaning and cultivating opera- 

 tions are purely preventive measures ; but now that more is known of the 

 life of the pest, they at once suggest possibilities in the keeping down of 

 numbers, and thus minimizing future attacks, 



14. — Summary. 



1. This paper deals with the flax flea-beetle {Longitarsus parvjilus Payk.), 

 a serious insect enemy of flax, and one responsible for considerable loss to 

 growers of this crop in Ireland. 



2. The history and synonymy, identity, distribution, and allied species are 

 discussed. In Ireland the species is commonly found all over Ulster, and of 

 recent years it has become a pest in flax -growing districts in Co. Cork. 



3. The adult is a leaf-eater, and causes serious damage to brairds of flax 

 seedlings. By eating the cotyledons and growing point many of the seed- 

 lings are killed outright, while others remain small and stunted, and many 

 become branched. 



4. Cultivated flax is the favoured food-plant of the adults, bub they also 

 eat clovers, grasses, and species of wild flax. 



5. Past records of damage to flax are given, with a discussion on the 

 conditions which probably favour attacks. 



6. The life-history has been followed, and the immature stages are 

 described and figured for the first time. 



