355 



trees. In detailed laboratory tests and as applied to single trees in 

 the orchard, nicotine sulphate (40 per cent.), " Black-leaf 40 " as an 

 ovicide, and nicotine-arsenical combinations in applications near 

 hatching time, have proved most effective, a three-fourths control 

 having been secured. Sea-moss stock at the rate of 5 lb. to 50 U.S. gals, 

 of water, and a calcium-casein preparation at the rate of 1 lb. to 

 50 U.S. gals, of water, when combined with this insecticide, were found 

 to increase considerably its spreading and sticking possibilities. 



These experiments have suggested the removal and the destruction 

 by burning or otherwise of all infested twigs of nursery stock and 

 young orchard trees. This measure would be of most value in the 

 spring. At that time the terminals are infested by small numbers of 

 overwintering and first brood larvae, whose destruction will decrease 

 considerably the size of the summer broods which cause widespread 

 injury. By cutting-back severely each year a few trees in a single section 

 of an infested orchard, the resulting fresh growth on these " trap 

 trees " should attract the moth, and the succulent shoots would 

 serve as a feeding ground during the spring and early summer for the 

 caterpillars. These trees may be examined frequently, and the 

 infested twigs removed and destroyed. In bearing orchards fruit 

 infestation might be decreased materially in this way. Applications of 

 nicotine sulphate (40 per cent.), " Black-leaf 40 " diluted 1 part to 

 800 parts of water, may be made about 17th May, 2nd June, 26th July 

 and 28th August. Life-history studies in 1918 and 1919 have shown 

 that the heaviest deposits of eggs are present on the foliage at these 

 dates. Clean culture, which would include the removal and destruction 

 by ploughing under or burning of all refuse (leaves, grass, weeds and 

 especially decaying and dried-up fruit) about the tree-trunks in 

 which the larvae find suitable quarters to cocoon for hibernation, is 

 also advisable. 



Some Insect Pests of the Castor Oil Plant. — Agric. Neivs, Barbados, 



xix, no. 470, 1st May 1920, p. 138. 

 Unlike Florida [R.A.E., A, viii, 235] Brazil is apparently free from 

 pests of the castor oil plant and contains districts eminently suited to 

 its cultivation. 



Moll (F.). Holzzerstorende Krebse. [Crustacea destructive to 



Timber.] — Naturwiss. Zeitschr.f. Forst- u. Landwirtsch., Stuttgart, 



xiii, no. 4-5, April-May 1915, pp. 178-207, 12 figs. [Received 



10th June 1920.] 



This paper reviews the existing knowledge of timber-destroying 



Crustacea, of which the most important species are Limnoria lignorum 



and Chelura terebrans. Most of the damage is done along the coasts 



of Europe and North America. Greenheart and turpentine logs, 



especially in the bark, are immune from attack. Sheathing and other 



similar coverings are too expensive, paints are not lasting, and 



impregnation with metal salts has not yielded good results up to the 



present. The best protection available, especially for pine wood, is 



impregnation with creosote. At least 160 litres of creosote must be 



used for 1 cu. metre of timber, and the creosote must contain 6-10 per 



cent, of tar acid. A large number of references to the literature of 



this subject, dating from 1723, are appended. 



