526 



sugar beets. On the exhibition field which was prepared in Jonkoping 

 in connection with the jubilee exhibition in that town, an attack was 

 noted on a plot on which autumn rye had been sown at different 

 dates. On the plot on which the rye had been sown earliest, the 23rd 

 of August, the rye began to turn yellowish-grey on the 11th of 

 Sej)tember. On closer examination the insects were found in such 

 numbers that a veritable cloud appeared above the plot when they 

 were disturbed with a stick. They were also found in the grass 

 round the plot, from which they had evidently migrated. By 

 the 19th September the rye was yellow and the following spring 

 the ground was quite bare, most of the plants being dead. The 

 attack was probably due to the unusually high temperature between 

 February and August and to the small rainfall. 



The insects lay their eggs on or in the leaves and the larvae hatch 

 in ten days. At the end of September imagines appear, and if the 

 climatic conditions are favourable, the eggs laid by them hatch, 

 otherwise they hibernate. The nymphs do more damage than the 

 imagines, being more stationary. According to Tullgren, there are 

 two generations a year in Sweden. 



EosTRUP (Sofie). Forsog med sprcfjtemidler mod bedelus (Aphis papa- 

 veris). [Experiments with sprays against Aphis papaveris.] — 

 Beretning fra Statens f rrsr^gsvirksomhed i pJantekidtur, 92, K0ben- 

 havn, pp. 234-256, 1915. 



In 1911 in Denmark, experiments with sprays, including nicotine 

 sprays, against Aphis rumicis [papaveris) were conducted, but owing 

 to the want of exact knowledge of the composition and strength of 

 the latter, no reliable results were obtained. Therefore in 1913 and 

 1914 analyses of the nicotine sprays w^ere made and experiments 

 carried out in order to ascertain the strength and quantity of sprays 

 giving the best results. The plants sprayed were seed turnips and 

 especially horsebeans, the latter crop being chosen as it is more liable 

 to attack from A. rumicis than any other plant. The results of the 

 experiments are summarised as follows : (1) Pure nicotine and extract 

 of tobacco are of the same effectiveness, the result depending only on 

 the percentage of nicotine. (2) The addition of soap does not increase 

 the effect of the spray, nor is soap solution alone very eft'ective. (3) 

 Pyridine is quite ineffective. (4) O'l per cent, of nicotine is sufficient, 

 and when the attack is not serious even less may be used, although 

 0*05 per cent, probably is too little. (5) It is necessary to use plenty 

 of spray as the plants must be thoroughly wetted ; for horsebeans, 

 15 gals, per acre are necessary. (6) A sufficient amount of spray is 

 more necessary than a high percentage of nicotine, thorough spraying 

 with 0'05 per cent, solution giving a far better result than using half 

 the amount of a 0*1 per cent, solution. (7) The fluid is more effective 

 against the young plant lice than the full-grown ones and better against 

 the wingless than against the winged lice. Macrosiphum (Siphono- 

 phora) pisi, a large species often occurring in company with A. rumicis 

 is more resistant to the spray. Coccinellids in all stages, Sitones 

 lineatus and thrips were found alive on the plants, whereas Lygvs 



