569 



majority of them occurs near the surface, they must be destroyed by 

 means of soil disinfection. The development of the deep-lying cysts 

 that cannot be reached in this manner must be hastened by sowing 

 repeatedly plants exercising a stimulating action. The brood will 

 then perish for lack of food-plants if the field is left fallow after the 

 ground has been broken up. 



Kaufmann (O). Ueber das Vorkommen von zwei Generationen bei 

 Kohlerdflohen. [On the Occurrence of two Generations in 

 Cabbage Flea-beetles.] — N achrichtenblatt deutsch. Pflanzenschntz- 

 dienst, Berlin, ii, no. 9, 1st September 1922, pp. 73-74. 



Observations in 1922 indicate that Phyllotreta undulata has tv/o 

 generations a year in the Naumburg region. Previous mention of 

 more than one generation is found in the older literature, but as flea- 

 beetle larvae were first studied by Bonier and Blunck [R.A.E., A, ix, 

 138, 547], such statements appear to have been based on supposition 

 only. Blunck believed that P. undulata leaves its winter quarters later 

 than P. nigripes and P. atra and takes longer to become mature. The 

 author, however, found that whereas P. undulata had left its winter 

 quarters by 18th April, the last individuals of P. atra only did so on 

 30th May ; while an examination of both species on 28th April showed 

 that 72 per cent, of the females of P. undulata were ready to oviposit 

 and none of P. atra. The latter matured later, 86 per cent, of the 

 females being ready to oviposit on 10th June. The appearance of the 

 new brood agrees with the above conditions. By 7th July females of 

 P. undulata were fully mature and many were already fertilised. 



WiLKE (S.). Die Runkel- oder Riibenf liege {Pegomyia hyoscyami, 

 Panz.). [The Beet Fly, P. hyoscyami.] — Beilage, N achrichtenblatt 

 deutsch. Pflanzenschutzdienst, Berlin, ii, no. 9, 1st September 1922, 

 2 pp., 4 figs. 

 This leaflet briefly describes the habits and control of the beet fly, 

 Pegomyia hyoscyami, Panz. In Germany two or three broods occur 

 in a year according to the climate. The most serious damage is done 

 by the larvae of the first generation, because the plants are young and 

 tender and have more difficulty in overcoming the injury. All infested 

 leaves must be collected and burned, and if the heart of the plant is 

 uninjured, a liberal top dressing of ammonium sulphate or sodium 

 nitrate will repair the damage. Thinning out should be delayed until 

 the larvae appear, and all infested plants must be collected and 

 destroyed. In sunshine the larvae die if the plants are left to wither 

 on the ground. After harvesting, the ground must be ploughed to a 

 depth of at least 15 in. so as to destroy the hibernating pupae. Early- 

 sown beet seems to suffer more than late-sown. A Braconid, Opius 

 nitidulator, Nees, parasitises the larvae and may prove very useful. 

 Birds, especially starlings, also destroy man}/ larvae. 



Will (J.). Die wichtigsten Forstinsekten. [The most important Forest 



Insects.] Second edition, completely revised by M. Wolff and 



A. Krausse — Neudamm, J. Neumann, 1922, xvi -j- 209 pp., 



203 figs. Price 440 marks plus 200 per cent.* 



The first edition of this elementary text-book for forestry students 



was published in 1905. While leaving the original division of the text 



* The N achrichtenblatt fiir den deutschen Pflanzenschutzdienst gives the price as 

 50 Marks plus 200 per cent. 



(7933) 2 Q 



