285 



whereas 1 to 20 proved injurious to the plants. One U.S. gall, of the 

 mixture is required for 200 plants. A solution of borax, based on the 

 measures recommended with this substance to kill house-fly larvae, 

 proved useless against those of P. brassicae. 



Henke (L. a.). Corn at the College of Hawaii Farm. — Hawaiian 

 Forester & Agriculturist, Honolulu, xvi, no. 2, February 1919, pp. 

 40-45. [Received 7th May 1919.] 



It is believed that leaf-hoppers [Peregrinus maidisl are an important 

 factor in causing stunted growth of maize plants in lower ground in 

 Hawaii, and experiments made to ascertain the relative immunity 

 of certain species of maize to attacks of this kind are described. Cuban 

 maize, although not absolutely immune, offered most resistance to 

 attack. June and Guam maize proved fairly free from leaf -hoppers, 

 but owing to the tendency in these varieties for the husks to open 

 before the harvest, the ears become infested with larvae of the grain 

 weevil, which is very abundant in Hawaii, and the exposed tips are 

 attacked by birds. On Laguna maize, leaf-hoppers were present 

 in great numbers, but did not completely destroy the crop. 



Chaine (J.). Destruction du Puceron du Rosier par les grandes 

 Chaleurs de I'Ete. [Destruction of the Rose Aphis by the Intense 

 Heat of Summer.] — Bull. Sac. Etude Vulg. Zool. Agric, Bordeaux, 

 xviii, nos. 3-4, March-April 1919, pp. 23-25. 



It is stated that a sudden spell of heat is fatal to Aphids on rose 

 trees. In 1911, a single day of excessive heat resulted in the death 

 of all rose Aphids, and these remained on the trees in a scorched 

 condition. In 1918, the same phenomenon was observed as a result 

 of a long period of high temperature accompanied by excessive drought. 

 In this case the Aphids died off gradually. 



Vayssiere (P.). L'Acclimatation des Insectes auxiliaires et son 

 Importance au Point de Vue agricole. — Bidl. Soc. Nat. AccUmat., 

 Paris, Ixvii, no. 5, May 1919, pp. 137-141. 



In discussing the natural methods of control of insect pests, the 

 view is expressed that the method of disseminating parasitic fimgi 

 among them, while excellent in theory, leaves much to be desired 

 in practice [see this Revietv, Ser. A, vii, p. 199]. The introduction 

 and propagation of insect parasites has yielded far greater success. 

 Some account is given in the present paper of well-known examples 

 of the successful establishment of such parasites, and the author 

 hopes to encourage further sunilar introductions into France and 

 her colonies, 



Bertrand (G.). Sur la haute Toxicity de la Chloropicrine vis-a-vls de 

 certains Animaux inf6rieurs et sur la Possibility d'Eraploi de cette 

 Substance comme Parasiticide. — C.R. hebdom. Acad. Sci., Paris, 

 clxviii, no. 14, 7th April 1919, pp. 742-744. 



The idea of utihsing as insecticides some of the poison gases 

 employed in the War led the author to experiment with chlorpicrin. 

 This is a mobile liquid that evaporates rapidly and is non-inflammable, 



